FAQs on the Zebra Danios Health

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FAQs on the Zebra Danios Health

Glofish Danio - Crooked Tails and Red Spots? 11/9/09
Hello! I've found lots of information about fish TB and bacteria issues from both here and Google, but am not sure what to do about my current situation.. I'm hoping the crew can help!!
<Will try.>
I've had a 5 gallon tank up and running with 4 zebra Danios (Glofish, to be specific - 1 male and 3 females) for probably around 7 to 8 weeks now (I regret not using a 10 gallon tank and I'm sure that once I get home for the winter break I will be upgrading to a 10 gallon).
<Do bear in mind [a] Danios should be kept in groups of 6 or more; and [b] even a 10 gallon tank is too small for this species. You need a tank at least 50-60 cm long given their size and activity level.>
All is well in the main tank and they've been an absolutely wonderful edition to my dorm room thus far. Test kits are indicating that the water is stable as far as PH and hardness go, although I need to find a more accurate test for my ammonia and nitrate/nitrite levels.. especially since this is a newer tank.

About a week after the fish had been added to the tank, I'd noticed that they had managed to spawn and many of the eggs had dropped down into the gravel and hatched. I did a regular water change and caught maybe 15 of them and put them aside in a separate bucket, using some of the water from the main tank. Many of them were a bright green color, I couldn't resist!
<And in doing so, bizarrely enough, you were breaking the terms of the license you accepted when buying these fish. While this might not be something you're terribly bothered about, here at WWM we do need to make this crystal clear to avoid any problems with lawyers.
http://glofish.com/license.html
>
It's been about a month and a half since I first found them and my numbers are down to 6. I've upgraded them from a little bucket to a 1.5 gallon Betta tank with a small filter with enough water flow to keep the water from becoming stale, but not too much as it overpowers the fry easily ( the intake tube is covered with mesh so they won't be sucked up into it).
<When rearing fish fry, use an air-powered sponge filter.>
25% water changes are performed usually every one to two days on the fry tank, and every week for the adult tank.
<OK.>
A week and a half ago, one of the fry refused to eat, mingled at the bottom of the tank, and ended up basically swimming on it's side, and laying down in the gravel.
<Likely a water quality problem, or perhaps inadequate diet.>
I isolated this fish in one of the original buckets, and in a few days it seemed back to normal, so I added it again into the main fry tank (which now seems like a bad idea). Since they're so darn small, I only noticed a few days ago that about 4 out of the 6 fry seem to have crooked tails. The back will taper like normal, but where the tail fin begins, their body's seem to make a relatively jagged swing to the left or right. It doesn't appear to be inhibiting their swimming, nor their livelihood, but I can't help but worry.. is this normal for Danio fry and should I be concerned?
<No, it isn't normal, and usually such developmental problems imply either [a] inbreeding or [b] poor environmental conditions. One very common misunderstanding is that because fry are small, they don't need a big tank.
In fact they're often more sensitive to environmental problems than the adults of the same species. I use 8-10 gallon tanks for rearing fry.
Anything smaller is a false economy. You can't rule out inbreeding though, given how inbred Glofish are to begin with.>
I've also noticed that they all have small red spots around the swimming bladder, spine, belly, etc, which is never a good sign.
<Indeed not; does sound like a water quality issue.>
Some only have a few, others have it all over (internally, not externally).
This also I only noticed a few days ago, particularly because these fry are so small and it's really only visible on the clear ones that didn't inherit the fluorescent gene.
<Indeed.>
Would this most likely be classified as a bacteria infection or TB or something of that nature?
<Bacterial, yes, but caused by the environment.>
If so, what on earth can I do? I would prefer to not kill them, especially since one of them is the actual fluorescent green that they're supposed to be, not the yellow version they're selling in stores, and another is red. Though I do plan on upgrading to a 10 gallon tank and expect only 4 of these fry to live through the next few months (if any), any other fry found will not be kept as I don't have the room, nor am I sure of how close the original four are relation wise (the current fry are of course related, haha.. let's not tango with probably already awful genetics by inbreeding some more).
<Indeed.>
Currently none of the adults are showing any of the symptoms that the fry have.
<Is often the case; adults will resist changes in environmental parameters than fry cannot.>
Any suggestions or ideas as to what might be going on or what I can do to keep these 6 from dying off, especially since I've kept these 6 in stable condition for several weeks now? Any and all thoughts are greatly appreciated!
<Would plan on using the 10 gallon tank for rearing fry; equip with a sponge filter and a heater, but otherwise leave empty. Keep clean, and perhaps use anti-fungal medication (even something like Melafix) through the first few weeks. Most any book on fish breeding will cover the basics; I particularly like "A Fishkeeper's Guide to Fish Breeding" by Chris Andrews, a book you can literally pick up for a penny on Amazon. It covers Zebra Danios, and what goes for them goes for these fish, since they are Zebra Danios except for one different gene.>
Thanks much!
~Steph
PS: An image of 2 of the fry with crooked tails can be found by following this link:
http://img.photobucket.com/albums/v462/Artsywolven/Crooked_tails.jpg
Unfortunately, I couldn't manage to catch any images of the red spots they have, seeing as they're so small and my camera can't take pictures of them that well.
<Cheers, Neale.>

Danio (Glo-Fish) with bent spine 8/14/09
Hi,
<Hello,>
I just stocked my aquarium this past Sunday (using a bottle of Tetra's Safestart) and noticed immediately upon bringing the fish home from the store that one of the new red Glo-Fish had a strangely bent spine.
<Not uncommon. Danios are very easy to breed, so when the Glo Fish craze caught on, lots of people bred them to satisfy the demand among those aquarists interested in such fish. Needless to say, where there's a seller's market, quality goes down as breeders fall over themselves to get as many fish onto the market as they can. This involved practises such as inbreeding, the purchase of minimally small starter populations with little genetic variation, and the accent on the numbers of fish raised from each batch of eggs rather than culling the weaker ones to ensure only the best are reared to maturity. End result, not all the Glo Fish on sale are good quality specimens.>
It seemed to be swimming normally with the others through yesterday afternoon. (With 5 Glo-Fish I might not have noticed if this particular one wasn't eating, although I'm paying much more attention now to each individual fish's eating habits). Although it was relatively active yesterday afternoon, last night we found it dead, half-stuck in the tank's filter inlet.
<Well, besides having a deformed spine, it also looks underweight, and likely isn't in the best of health. Danios are aggressive fish amongst themselves because of their fiercely hierarchical school structure. You must always keep more than six specimens, otherwise what commonly happens is the dominant male works his way through the others, stressing them to death. This is a common mistake beginners make, purchasing three or four Danios and then wondering why, six months later, they only have one (or sometimes two, each one patrolling different ends of the tank). I can't stress this point strongly enough.>
Attached is a picture showing the oddly shaped back on this fish. My first question is whether this bent spine indicates TB,
<No, it's not TB. Whatever gave you that idea?>
and if so, what I should do about the other fish in the tank (4 Glo-Fish and one Betta).
<Danios will, as is widely know, nip at Bettas. Danios need a tank 60 cm/2 feet long, minimum, given their potentially fairly substantial size, upwards of 5 cm/2 inches. They are also hyperactive, and need relatively cool (around 24 C/75 F) water with a strong current, whereas Bettas need warm (around 28 C/82 F) water with a gentle current. So there's no way to keep the two species in one tank.>
Also, I'm concerned that the orange Glo-Fish isn't thriving -- it didn't seem hungry today even though I offered it brine shrimp in the afternoon (which the others go crazy for).
<Live brine shrimp make good snacks, but don't use more than once or twice a week: they contain virtually no nutritional value at all. Concentrate on a good, balanced flake or mini-pellet food, such as Tetra Min or Hikari Micro Pellets.>
It also doesn't seem to be growing/moving as actively as the others, although it is still swimming around. In contrast, the other fish (two greens and one red Glo-Fish and a Betta) have been eating well and seem quite active. The Glo-Fish all came from the same tank in the fish store, but the Betta was housed separately originally. Should I separate the orange Glo-fish asap?
<If you want. It may recover some strength and vitality given the chance to feed normally; mixed with just three other Danios, you already have a stress nightmare for the species, and this poor chap is right at the bottom of the pecking order.>
Return all the fish to the store (they have a two week warranty)?
<If you want. If this tank isn't big enough for Danios, you shouldn't be keeping them anyway.>
Empty the tank and start all over again? (It's an Oceanic BioCube.)
<What size? The 14 gallon one has no value at all for keeping Danios, but the 29 gallon one would be okay.>
A side question: is the Biocube's filtration system too strong to be suitable for a Betta?
<Probably. Bettas do best with air-powered sponge or box filters. Cheap, reliable, easy to use.>
Occasionally, the Betta seems to get caught in a strong current and carried halfway across the tank before it stabilizes itself.
<Obviously not good.>
Or is this a sign of some illness?
<No, merely bad choices on your part.>
The tank's temperature has fluctuated a little (from a low of 78 to a high of 82), but for the most part has stayed around 79-80.
<Far too warm for Danios in the long term. Do read up on the needs of species prior to purchase, preferably in books or at least in web sites written by recognised experts rather than people selling fish.>
Thanks for your help.
<Cheers, Neale.>

Re: Danio (Glo-Fish) with bent spine 8/15/09
Thanks for your detailed answer.
<Ahh, Neale is marked "out"; BobF w/ you now>
Yes, it looks like the advice we received from the store was not very reliable -- ("great tank for those fish -- they should be fine together"), just as the specimens were not very strong, either. So what kind of fish do you consider appropriate for the 14 gallon Oceanic BioCube?
<Smallish species that are easy-going temperament wise... Please read here:
http://wetwebmedia.com/ca/volume_5/volume_5_3/stocking.htm>
Another Glo-fish (one of the aggressive, healthy-looking, large-appetite green ones) was found dead this morning. This whole experience is actually quite depressing for me. Given the need for more than 6 Danios (and I thought buying 5 at first was pushing things because it was a new tank), should we immediately re-stock with 4+ more Danios?
<Mmm, no... Wait till the system is fully established; at least in terms of biological cycling>
Or might the deaths be due to new tank syndrome and we should give them a few weeks before introducing more?
<This last>
If they're likely to pass away soon, what should we replace them with, given our tank constraints? (My daughters have their eyes on the fancy guppies and some cories.) My fish TB question was based upon comments on your site linking "bent spine" with "fish TB," but I couldn't find pictures to try to analyze whether the crooked spine of my Glo-fish was the same look as the bent-spine-from-fish-TB.
<I saw this... and do differ in opinion from that which seemed to be stated. Mycobacteria might be involved... but I hasten to point out that this genus is almost omnipresent in captive aquatic systems... what is really germinal in its expression is environmental conditions, predisposing genetic and developmental circumstances that promote such expression>
Thanks again for your advice.
<Welcome. Bob Fenner>

Re: Danio (Glo-Fish) with bent spine 8/16/09
"<I saw this... and do differ in opinion from that which seemed to be stated. Mycobacteria might be involved... but I hasten to point out that this genus is almost omnipresent in captive aquatic systems... what is really germinal in its expression is environmental conditions, predisposing genetic and developmental circumstances that promote such expression>
Thanks again for your advice.
<Welcome. Bob Fenner>"
<<Bob, if I may, let me just add a comment to two. Whilst I agree Mycobacteria are likely troublemakers in many tanks, and certainly Mycobacterium marinum (the specific Fish-TB bacterium species) troubles hobbyists from time to time, my gut feeling is that Fish-TB simply isn't that common. Bob may have a different feeling for this, but I'd reckon of every ten freshwater fish stated by their owners to be sick from (or killed by) Fish-TB, likely only one of those fish is actually suffering (has suffered) from said disease. The incidence of other problems, in particular "New Tank Syndrome" as well as chronic malnutrition, careless use of feeder fish, antagonistic social behaviour, and so on likely account for far many more deaths. Outside of a microbiology lab, it's impossible for us as hobbyists to positively ID cases of Fish-TB, but the flip side is that it is almost always a better use of your time to review the issues mentioned above water quality/chemistry, diet, aggression. Reviewing those issues will catch many more problems than Fish-TB paranoia, and likely provide you the data you need to effect your own remedy. In the case of Danios, simply keeping them in a large (20 gallon+) tank with relatively cool water and plenty of current will go a long way to preventing problems. Danios on the whole sail through the cycling process, provided the aquarist performs frequent (ideally daily, but certainly every second day) water changes around 20-25% and avoids overfeeding by offering food every other day. Do that for the first 3-4 weeks, and Danios are about as good a fish as their is for new tanks. Glo-fish Danios will inevitably be less hardy than the real things, but still, judicious use of your nitrite test kit should help you detect serious problems before they happen, and water changes will keep conditions in the tank tolerable. Cheers, Neale (Stuck at CVG airport for the next 4 hours, so may well look through the WWM inbox!).>>
<I do concur that Mycobacteriosis is quite often ascribed where it is not a primary "causal agent" of aquatic ornamentals, however the genus is indeed quite common in both marine, fresh and brackish settings, and can be a cause of spinal deformity... Further, I do strongly agree with your assessment concerning prevention... good water quality, nutrition, under-crowding prevent almost all cases. I am more concerned with the occasional granulomatous troubles hobbyists suffer from broken skin, septic conditions in their too-"dirty" systems and this contagion... Lastly, a personal note. An old acquaintance, Stan Sniezsko, did a good deal of real science work, popularized the fact that humans (from the "consumption" years back) could pass Mycobacteria to fishes (and now known vice versa)... And very ultimately, bon voyage. BobF>

Zebrafish TB? (RMF, opinion?) – 06/12/09
I recently moved about 50 Zebrafish into a 10 gallon tank (about 2 weeks ago).
<Sorry, is this a typo? Fifty Danio rerio! In a ten-gallon tank! Seriously, this isn't going to work. Even using the somewhat unreliable "inch per gallon" rule, your tank is one-fifth the size it needs to be. If this is for lab work, as I suspect given your e-mail address, then your problem isn't just animal cruelty but bad science. I make this point as a (PhD) biologist who's worked in, or visited, more than a few zoology labs in his time. Labs that take animal welfare seriously are the ones that produce good science because they're able to control all the variables like intraspecific aggression and metabolite toxicity most reliably.>
I noticed one of the fish had a severely bent spine but assumed a genetic defect.
<Not uncommon for one in fifty commercially-farmed or tank-bred fish to have this type of deformity; the lack of natural selection coupled with high levels of inbreeding mean that the quality of offspring produced in
such ways isn't high. Poor water quality only makes things worse because it leads to non-genetic developmental problems and mortality.>
After a couple of days a brown biofilm started to build up on the tank walls and plastic plants.
<Likely diatoms; these are golden-brown and feel greasy. Very common in poorly illuminated tanks with variable or poor water quality. In themselves quite harmless, and the least of your problems.>
I had to remove this every couple of days. The tank water was kept between 24-26 degrees C, fish were fed flake food/Artemia daily.
<Much too warm for Danio rerio; it's a subtropical species that does best around 20-22 C. As you doubtless know, the warmer the water, the less oxygen in contains, and the faster the fish respires -- so keeping them excessively warm causes problems as oxygen demand falls below oxygen availability. If all else fails, consult Fishbase with regard to optimal conditions; while it isn't 100% reliable in terms of *aquarium maintenance* as opposed to the wild, it's a very good start.>
I used a regular flow through filter system with a bio filter. A couple of days ago I noticed that another fish had developed a curved spine. The fish were eating and swimming normally though so I just changed 25% of the water and the foam filters.
<Until you upgrade this tank, you should be changing 25% of the water daily. Also, don't forget that cleaning a filter doesn't mean killing the beneficial filter bacteria, so approach this task cautiously!>
I left for a day with instructions for a friend to feed and check on my fish which they didn't do.
<In itself, leaving an aquarium unattended for 24 hours shouldn't be a problem at all.>
So 36 hours later when I got back half my fish were dead and the tank was a mess.
<Certainly not your friend's fault. Your fishkeeping skills are to blame here. You really cannot expect these fish to survive in this tank.>
A lot of the fish were in pretty bad shape and it seemed like a few more had the spine problem.
<Dismal.>
Other than that it was hard to notice any signs as the fish were in rough shape. The twenty or so fish that survived are being treated with LifeGuard as I suspect mycobacterium infection.
<On what basis? Mycobacteria infections are fairly rare, and in your case, the problem is almost certainly water quality. Have you yet checked ammonia or nitrite levels?>
I have another tank where I recently moved 5 fish from the now infected tank, but the other tank is fine. Both tanks contain fish from the same supplier but only one tank has the biofilm and spine problem. Any ideas??
<For the love God, please think about what you're doing. If this is a science project of some sort, how about starting with the basics, like what Danios need to thrive in aquaria. This information is widely described in aquarium books. Next up, bear in mind these are animals, not computer simulations, and certainly in England, this kind of dismal treatment of vertebrates in labs would be considered animal cruelty. You cannot possibly expect good science from a tank where half the fish die within a week, either. So on multiple levels you have a lot of work to do. Forgive me for having a bee in my bonnet about this, but over the years I've seen too many undergraduates and masters students maintaining animals in squalid, lethal
conditions. It depresses me to think about how much casual suffering goes on in universities and research labs. I'm not against animal use in labs at all, but such animals should be treated properly, and I fear this isn't the case here. Cheers, Neale.>
<<Not likely mycobacterial... but manifestation of poor husbandry... A very good/bad example here of total disjunction betwixt "science" and practical aquariology. BobF>>

Re: Zebrafish stocking density/temperature – 06/12/09
A ten gallon tank is 34.27 L, so my stocking density is less than 2 fish/liter (this is well below the maximum stocking density of 10 fish/liter for adult Zebrafish). Also the other tank (same size) has 45 fish in it and they are doing just fine. I have had them in there for the last 5 months without any deaths. These fish are eating properly and growing. If you look at some recent publications regarding fish husbandry you will see that my stocking density is well below the norm. "All fish were maintained at 27°C using a 14-h/10-h cycle of light and darkness at a maximum stocking density of 10 adult fish per liter of water." Lucia N. Vojtech,1,2 George E. Sanders,2,3 Carla Conway,2 Vaughn Ostland,4 and John D. Hansen. Another paper: -- "They were acclimated for 2 weeks in glass aquaria, in 40 L of dechlorinated Hamilton city tap water (for ionic composition, pH, and hardness, refer to 14), at a stocking density of 10 fish L-1. The water was maintained at 28 °C by submersible heaters and filtered through appropriately sized multi-stage external power filters (which included mechanical, chemical, and biological filter components). The water was returned to the aquaria by a “waterfall” return which also ensured adequate aeration. Feeding was twice daily with a commercially available tropical fish flake diet. Fish were maintained and treated according to ethical guidelines established at McMaster University and covered by AUP 06-12-65." Characterization of a Radiation-Induced Stress Response Communicated in Vivo between Zebrafish- Carmel Mothersill,*†‡ Richard W. Smith,† Nalini Agnihotri,‡ and Colin B. Seymour
<You can't possibly expect Danio rerio to do well under such conditions. Do note that these scientists are maintaining their fish for short periods. But for all that, the guys who actually know how to keep Danio rerio properly -- aquarists -- would never dream of keeping these fish at such stocking levels. I have been to multiple labs in my time, and seen a lot of animals being kept very badly. Sure, they publish papers saying all kinds of stuff. But what they don't advertise is the attrition rate in their labs: how often animals, particularly fish, die. Do these Danios live the full 4-5 years they should do? I doubt it. Are they constantly having to treat for disease, or top up stocking levels with new livestock? Yes. I've been to labs producing good science on the back of bad fishkeeping, including things like Danios, Killifish and Tilapias. If you're asking me why your Danios are sick, I'm telling you: you're keeping them wrong. Forget the scientists -- they don't know what they're doing -- and look at the aquarium literature. Danios have been kept and bred for something like a hundred years. We know what we're doing.>
For Zebrafish "The maintenance temperature of 28.5 °C recommended by Westerfield (1995) is almost universally cited for Zebrafish in culture and the wider range of 24–30 °C is recommended by Matthews et al. (2002)" - The husbandry of Zebrafish (Danio rerio): A review Christian Lawrence. Also see the temperatures used in the papers above.
<It's still too warm. Again, keeping them warm speeds up their metabolism, which increases growth and maturation rate, which might be fine if you're after certain sorts of data. But does it help the Danios stay healthy? Of course not. In the wild, these are SUBTROPICAL fish from things like lowland streams and rice paddies. Feel free to go against evolution if you want, but you know you'll lose.>
The fish were in the tank for 2.5 weeks prior to the recent deaths and before this were kept in a 15 gallon tank for 5 months with no incident. If you look at the literature regarding Zebrafish husbandry you will realize that the stocking density and temperature of my tanks is not the issue.
<Yes it is. It's this sort of casual indifference to what animals need to be happy that gives zoology a bad name. Just to repeat, I am a scientist; I have a BSc in zoology and a PhD in geology. I've got a stack of papers to my name, and I've written a textbook on cladistic phylogenetics, not to mention my stuff on palaeontology and of course fish. So I'm not some tree-hugging freak who dislikes lab work on principle. But please understand this: the reason your Danios are sick is because you're keeping them at an insane stocking density, and at a temperature that likely puts additional stress on them in terms of oxygen consumption versus oxygen availability. What other people did when writing their papers shouldn't be an issue: use your initiative, read the aquarium literature, and adjust your husbandry methods accordingly. In other words, be an ethical, efficient scientist rather than someone who throws animals through a grinder until you can pulp out some data just about good enough to throw onto a paper. Until you fix the conditions your animals are being maintained under, treating the fish is largely irrelevant. Better yet, use the ammonia and/or nitrite test kit I'm sure a good scientist like you has, and test the water. If you detect levels of either above zero, then there's empirical proof that the water is toxic. From there, it's not much of a leap of deduction to establish that if the fish are being kept in toxic conditions, they're going to get sick. If the water has zero ammonia and zero nitrite, and does so a different times of the day and between (at least) weekly water changes, then you will at least be able to tell me -- with some credibility -- that the environment isn't the issue, at least in this regard. So what are you going to do, cling to some idiotic papers, or else actually grab a test kit and check out the water quality? A good scientist could make only one decision. Cheers, Neale.>

Danios, science and posing as such, the/a human condition – 6/12/09
Bob,
<Neale>
The Danio e-mail was interesting. I wish I could have dropped some names, but I've seen appalling examples of animal "care" in both US and UK universities. Besides being unpleasant to see, it also makes me wonder just how good the science is these guys are collecting when their animals must be severely stressed.
<Ah yes... too many, and current instances of "poor" science... actually, due to a lack of real controls non-science (alludes to nonsense)>
Those exact same scientists then wonder why we -- the taxpayers who pay them -- don't trust them when it comes to animal welfare and medical ethics!
<Yet another separate, though valid concern>
What really sticks in my craw is that most of the really casual cruelty is not medical research that at least has some practical value, but crappy stuff done by undergraduates and masters students!
Honestly Bob, one place I went, they had rows and rows of aquaria in which salamanders and other amphibians were being kept, but the students had got bored, and they'd all dried out, with the poor mummified animals left in them. There's no excuse, and if it was up to me, that would have been an animal welfare law suit right there.
Cheers, Neale
<Mmm, this and perhaps a case study for (non) ethics. Keep pushing toward the high-ground my friend. BobF>

Zebra Danios - red gills or normal 3/1/09
Hello Crew and Happy Weekend!
Bob, you were right, the Fish Yoda's work here is certainly not done. As Hans said to Luke "Great, kid. Don't get cocky."
Today I got my API freshwater master test kit, and test results at 2 p.m. were:
Ammonia 1.0
<Dangerous!>
Nitrite 0.25
<Tolerable in the short term. Does appear the filter is not "over the hump" yet. Do also check you're not in an area with chloramine in the water, and if you are, use a dechlorinator that removes it, as well as chlorine.>
Nitrate 40
pH 8.2
Test results at 22:15 were:
Ammonia 2.0 (highest result so far)
<I'll say. Cut back on food to zero.>
Nitrite 0.0
Nitrate 10
pH 7.8
I did a 30% water change at 2 p.m. adding Ammo-Lock and Nutrafin Aqua-plus to the new water. I think I will do a 50% water change tomorrow too. Do you think that's a good idea or should I do it tonight? The ammonia results with the API test were higher than with the Interpet tablet test, which concerns me because maybe I've had higher ammonia than my tests showed before. I'm also surprised that every reading changed so much in 8 hours, are those changes possible?
<If they happened, they're possible!>
The Rat Pack are going strong, and are scattering eggs every 3 days or so.
I have two concerns:
1) They are not swimming at the surface much, they're very active in the mid to bottom levels and were digging in the gravel today. I'm hoping that's because of the egg scattering and because there aren't any mid or bottom dwellers yet. They show no lethargy, are constantly moving, and are not gasping for air.
<That's a good sign. I'd trust this rather more than the test kits; test kits can be notoriously unreliable, and the ammonia test kit in particular
can test other chemicals in the water too. I forget which ones.>
2) Some of them seem to have reddish gills, but I'm not sure about this. I went online to compare pictures and some pictures look just like my zebras, but I'm concerned and hope I'm just being an overprotective parent. Picture attached. You can see the red 'dot' by their eyes, and when they're swimming I can see red inside when their gills flare out. Normal or not?
Do they have any red insides that could be showing through? Should I treat them to help them heal if they are damaged?
<Not normal, and can be a sign of ammonia irritation. Wouldn't do anything treatment-wise, but would reduce food to zero, do a 50% water change twice today or until the ammonia goes to sub-0.5 mg/l levels. Do check the filter is properly configured, e.g., you've bought the right media and then put the different media in the right order, that the filter is appropriate to the size of the tank, etc.>
Many thanks! Summer
<It'll take about 3-4 weeks for the ammonia processing to go from none to full whack, and then about another two weeks after than nitrite processing should be running at its full level too. So a ballpark figure of 6 weeks is often quoted. But this depends on various factors including temperature, oxygen, pH, etc. The optimal pH is just under 8 for the ammonia bacteria and just over 8 for the nitrite bacteria, so you're fine with regard to these. As for temperature and oxygen, what suits Danios suits the bacteria: around 25 C, with lots of water movement. While bubbles aren't the thing, the water should be shifting from the top to the bottom of the tank at a nice brisk pace. Other than these things, it's all down to time. Cheers, Neale.>

Update: Zebra Danios - red gills or normal 3/1/09
I decided to test the ammonia again, and got 2.0 again, so changed ~70% of the water. My verdict is it's best to be cautious.
<Would agree. Good luck, Neale.>

Re: Update: Zebra Danios - red gills or normal
<This is BobF, cutting in here... as this is a dire emergency and NealeM may be out (he's in the UK)>
I'm still having crazy ammonia after the 70% water change late last night and a 90% water change today.
At 3:00 pm today the readings were:
Ammonia 5.0 (oh my gosh - oh NOOOOOO!)
Nitrite 1.0
Nitrate 40
pH 7.8
temp 97.5 (I can't seem to get this temp down even turning off the heater and lights, but it is stable)
<!!! I am hoping the ammonia reading is spurious (do use another test kit), your nitrates are much too high... and anomalous with the ammonia... as if this system were cycling... there would be no ammonia... nor nitrite...
Just nitrate... Again, something is amiss here... I am almost positive it is with your testing/kit... as your livestock would be dead. The temperature as well is deadly high... turn your lights off, adjust your heater... Do you know how to do this?>
I immediately did a 90% water change. That took two hours, and now two hours later at 7:30 pm, my ammonia is back up at 2.0 and nitrite at 0.50.
That's with the API testing kit, and I tested the tap water with API to compare. The tap water result was 0.0 ammonia. I tested the tank water with tablets as well, and that result showed 0.0 ammonia. So my test results for the tank ammonia are currently ranging from 0.0 to 2.0!
<Toxic>
I'm preparing to do another large water change,
<Need to solve the source issue... not simply by massive water changes...
You need to introduce nitrifying bacteria... STOP feeding...>
but this is freaking me out.
I last fed the fish yesterday morning, they seem fine except some have the red gills I mentioned. All are very active and nobody is gasping for air; quite the contrary, they prefer swimming in the mid to bottom levels.
I'm not aware of anything dead in the tank, and I checked the filters to ensure all was in the right place, so I'm at a loss as to why I'm seeing these quick, alarming ammonia spikes in a 240 L tank with 6 zebras.
Any thoughts? Should I do another 90% change or 50% right now? My poor fish!
Thanks, Summer
<STOP and read here: http://wetwebmedia.com/FWSubWebIndex/fwestcycling.htm
and the FAQs files linked above... NOW. Bob Fenner>

Re: Update: Zebra Danios - red gills or normal
<Bob: thanks for your additional comments and catches. Summer: for what it's worth, I don't think there's actually anything wrong with your tank.
If the Danios are behaving normally, and you're doing 25% water changes at least every other day, and continue to do so for the next 2-3 weeks, I'd expect this tank to cycle safely. While not the "best" way to mature an aquarium, Danios have been used for precisely this process for decades, and if you do the water changes, without harm. Safe water should smell sweet, and the Danios shouldn't be breathing heavily, gasping, nervous, or otherwise stressed. I do suspect your test kits are wrong, or else you're using them wrongly. Do check you're adding the right number of drops, and you're holding the colour card up to a white light (daylight, ideally).
Test strips are flaky, and while fine most of the time, sometimes they're way off. Perhaps a manufacturing/quality control issue? I don't think your aquarium is as hot as your thermometer says, either. The standard 25 C (77 F) is barely warm to the touch, and in a centrally heated home, will actually feel slightly cool. Just a reminder: in a centrally heated home Zebra Danios are fine without a heater, so feel free to switch off the heater if needs be. They're subtropical fish with a high tolerance of cool conditions down to around 18 C (68 F), perhaps less. The bottom line is
this: if your fish are behaving normally, and you're minimising the food you give them, and you do regular water changes to dilute ambient nitrite/ammonia in the system, this tank will cycle normally. The only cautions are those relevant to biological filtration generally: ensure the filter is adequate to the size of the tank, and always remember to rinse the (biological) media in a bucket of aquarium water or running lukewarm water, but never hot water or using anything likely to kill the bacteria.
While cycling the tank, don't use zeolite chips (sometimes sold as "ammonia remover") in the filter media either, as these will obviously take the "food" away from the bacteria, slowing down the cycling process. Don't confuse this with ammonia-remover added to new water though; that's something else entirely, a liquid used to treat traces of ammonia sometimes present in drinking water. Cheers, Neale.>

Re: Update: Zebra Danios - red gills or normal
Thank you Bob for such a quick response. I'm doing my best here to fix this issue. I have unplugged my heater and turned the lights off and the temp still doesn't seem to drop even though it's about 73 in the room.
<Just leave all as is... reset the heater (elsewhere) to the upper 70's F... re-install and plug in within the tank... The temp. will come down (safely) on its own>
I tested my thermometer and it seems to be correct.
<The water should feel very warm...>
The tank is only 2 weeks old
<Hmmm, should NOT have aquatic life present>
and is cycling, so I'm not sure if I understand your comment "as if this system were cycling".
<The NO3, nitrate is evidence that it is indeed cycling... though not completely "cycled"... as the predecessor molecules (ammonia and nitrite) are still present... AGAIN, PLEASE READ where you were referred to>
How do I introduce nitrifying bacteria? I've added Nutrafin Cycle to the water. Anything else I can do?
<No... just time going by>
I've gone over the website you said to read many times, but will do it again
NOW.
<Good. B>

Re: Update: Zebra Danios - red gills or normal
Bob, you're right that something's amiss. There is certainly a problem with one of my testing kits or both! I have two kits, tablet and drops, and the tablet shows ammonia at 0.0, drops show ammonia at 4.0. Tomorrow I'm going to buy another kit.
<Ahhh! I strongly suspected as much. The stated high amount of ammonia would be deadly>
The fish are not showing signs of distress, so I will wait on the water change especially considering I did a 90% change today, and two large water changes yesterday (30% & 70%).

Re: Update: Zebra Danios - red gills or normal
Bob & Neale, I send you both a giant, big hug THANK YOU. I'm calming down now. Using your valuable input, my deduction is that I likely have a bad combination of two faulty water test kits and a faulty digital thermometer.
<Makes sense.>
Bob, I did read the website, I promise! I still don't know the nuances. I understand that nitrate means the tank is cycling, and was confused by my test results. I'm going to print that page and read it regularly until I can recite the biological process in my sleep.
<In big cities like London, the nitrate from your tap water can be as high as 50 mg/l; against that, detecting the increase in nitrate from the fish can be extremely difficult. So while Bob's advice that detecting nitrate implies the biological filtration process is occurring, detecting a rise from 50 to 55 mg/l isn't going to be east. The background nitrate level in London tap water varies too, so sometimes it's quite low, almost zero, and other times much higher. Ideally you test the nitrate of each batch of new water and then detect the nitrate level a week later in the aquarium. But realistically, that's a pain in the backside.>
And for the record, Neale advised me to do fishless cycling, and I did not follow his advice. I see the error of my ways, and won't EVER do that again.
<Once you've cycled on tank, you need never cycle another: filters can be "split" into two whenever you want, by donating live media to a new aquarium, instantly cycling it.>
My tank water feels cool to the touch, and is definitely not warm. I'm not sure if it smells sweet, but it smells nice and clean. The heater is unplugged. I have radiators, not central heating, and I keep my room temperature cooler than most.
<Ah, by "sweet" I mean precisely that, clean and fresh, as opposed to meaning sugary.>
I carefully follow instructions with the test kits and measure exactly the required mm, distribute the drops vertically and evenly, and always use good lighting with the test tube against the white background to determine the result. I don't use strips.
<Cool.>
I don't use zeolite chips and only once have rinsed the filters in the tank water. Ummm on that note, I inserted the carbon filter into the filter basket after I rinsed the others for the first time on Saturday morning. I can't recall why I decided to do that, but removed it that afternoon after I researched WWM and read that it was virtually of no use. All of these spikes occurred Saturday after the first/only time I rinsed the filters, could that have contributed to the spiked readings? Did I make a mistake rinsing the filter pads?
<Possibly, but I think not. Bacteria by their very nature are "hardy", and unless you do something really dumb, e.g., wash the media under a hot tap, the bacteria in the media should be more or less happy through any normal maintenance process.>
My Danios are if anything, curious and responsive. The second I open the aquarium lid, they swim right up to the top. I try to get water samples from areas away from them, but I have to trick them. It's as if they want to jump into the test tubes! And three times one of the Rat Pack has darted his way into my siphon while I change water. I'm just glad my siphon is wide and lacks enough suction to whip the kids into a bucket.
These zebras are curious and fearless and cheeky. I badly want them to live and feel horrible that they have red gills.
<Suspect they're fine. Fish do have red gills normally, since these are blood-rich tissues. If the fish are so small the gill covers (opercula) are transparent, then you'll easily see the red gill filaments.>
I am so appreciative of your time and advice! Summer
<Cheers, Neale.>

Re: Update: Zebra Danios - red gills or normal – 03/03/09
Hi Crew,
Here's a quick update - I didn't manage to get another testing kit today, and my *faulty* kit still showed outrageous ammonia and nitrite levels, so I did another 90% water change at 2 pm today. I tested again 30 minutes after the water change, and the results were pretty much the same, reinforcing there is a problem with the kit. I'm going into town tomorrow and will get another testing kit for sure.
The water temperature finally is down to 25 C, questionably considering my thermometer may be inaccurate.
The Rat Pack are active and still show no signs of stress. They look pretty happy right now, albeit maybe a bit hungry. They all rush to the top when I open the lid, and continue to swim in the mid to bottom levels.
How long can they go without feeding? Speedy G is cruising around too, when I can find him.
Take care,
Summer
<Does sound positive. Wouldn't worry too much about these fish. Keep doing what you're doing. If your Danios are happy and healthy, that's the main thing. Cheers, Neale.>

Re: Update: Zebra Danios - red gills or normal – 03/03/09
Oh, and I tested the tap water for nitrate today and it was at 20, so I'll test it regularly. I'm in Chiswick, West London.
<20 mg/l sounds about right for London. So given that, detecting nitrate doesn't imply that biological filtration has become established.
Coincidence time: one of my best friends (who happens to keep fish too, though marines) lives in Chiswick. She rates 'Tropicals and Marines' in Mortlake highly as her local LFS. It's a small, family-run store. If you visit that store, ask for Hamant and drop my name: he'll take care of you.
Cheers, Neale.>

Re: Update: Zebra Danios - red gills or normal – 03/03/09
Thanks and Tropicals and Marines is where I bought my tank, plants and fish! He was very helpful and has beautiful fish. However, he did sell me those non-aquatic plants you said to take out.
<Next time you're there, tell Hamant I'm slapping him on the wrist! I just wish retailers wouldn't stock these plants, or at least said to purchasers, "You do realise those plants you just selected for your aquarium can't live underwater?" Wholesalers may be to blame, sending 'variety packs' of plants, some of which are non-aquatics. But whatever the excuse, it shouldn't happen. Selling them to aquarists is basically a con. Cheers, Neale.>

Update, good result and thank you Re: Zebra Danios - red gills or normal, RMF 3/20/09
Hi Crew,
<Summer>
The last response I received from you was two weeks ago and a deserved slap on the wrist from Bob, which hurt but I take it as a lesson learned in not only being clear about the tank actions I've implemented, but also reinforcing my respect for the advice and experience of you Fish Yodas.
<Am about as cranky, though not quite as short, nor green...>
I can happily report that The Rat Pack and Speedy G are now living in a cycled tank!
<Yay!>
I was using nitrifying bacteria (Hagen Cycle, which I reported as Nutrafin Cycle) and also obtained a used filter from Aquatic Design Centre in London. All fish are still alive and thriving and thank you very much for your help. Bob, Speedy G decided to have little Ramshorns this week, some albino looking, and also at least one different conical snail has appeared (hmmmm). I think I might move Speedy G and The Rat Pack to a smaller tank and turn my 240 L into a cichlid tank. I also will set up a quarantine tank.
Thanks a million and I'm sure I will be in touch.
Best,
Summer
<Thank you for your uplifting follow-up. Excelsior! BobF>

Well, Bob, sure Yoda was a bit cranky, and also ~ 900 years old and just outright honest and straightforward and didn't waste time. Instead he was dishing out experienced and excellent advice. Call it cranky if you want
-
so yeah, you have those Yoda qualities and frankly I respect them much more than someone faffing about and being nice while I could be hurting innocent fish.
<Thank you my friend. B, who has a friend with a precious daughter by your name>

Awww, love to hear that about the precious girl and I hope she'll enjoy having such a unique name!
On that note, maybe I'll name a couple of my future fish Bob and Neale...nah, that's a bit over the top.
<Heeee! Seems reasonable to me. BobF>

Update, good result and thank you Re: Zebra Danios - red gills or normal, Neale's go 3/20/09
Hi Crew,
<Ave,>
The last response I received from you was two weeks ago and a deserved slap on the wrist from Bob, which hurt but I take it as a lesson learned in not only being clear about the tank actions I've implemented, but also reinforcing my respect for the advice and experience of you Fish Yodas.
<I'm not sure I like the idea of being short, green, hairy and with big ears. But that levitating X-wings thing is kind of cool.>
I can happily report that The Rat Pack and Speedy G are now living in a cycled tank!
<And I bet they're happy now!>
I was using nitrifying bacteria (Hagen Cycle, which I reported as Nutrafin Cycle) and also obtained a used filter from Aquatic Design Centre in London.
<Always a fun shop to visit.>
All fish are still alive and thriving and thank you very much for your help. Bob, Speedy G decided to have little Ramshorns this week, some albino looking, and also at least one different conical snail has appeared
(hmmmm). I think I might move Speedy G and The Rat Pack to a smaller tank and turn my 240 L into a cichlid tank.
<Why not mix Danios and Cichlids? Danios make superb dither fish for non-predatory but shy Cichlids such as Eartheaters and Acaras.>
I also will set up a quarantine tank.
Thanks a million and I'm sure I will be in touch.
Best,
Summer
<Have fun, Neale.>
Thanks Neale, and I associate you and the Crew as "Fish Yodas" for your teaching wisdom, not physical attributes! I'll reserve any short, green, hairy and big ear comparisons for when I meet you in person.

If it helps, feel free to associate me with Princess Leia, cute but bossy and clearly not good at taking advice, although I usually come to my senses in the end.
<Bossy perhaps, but a babe nonetheless! And a princess, too. Score!>
Maybe I will combine the Danios and Cichlids. I was more worried that the Cichlids would eat Speedy G.
<Some certainly will eat snails. But others will ignore them completely.
Acaras like the Keyhole Acara would be a particular recommendation. Or, if you're in a hard water area, some of the easier Tanganyikans like Neolamprologus brichardi, Julidochromis ornatus, or Neolamprologus leleupi would all offer some colour while ignoring surface-swimming dither fish such as Danios.>
I've formed an attachment to this lively Ramshorn snail. Just recently, Speedy G seems to enjoy floating in the water currents. Have you witnessed snails "flow jumping" like that, and are they even capable of joy or am I anthropomorphising?
<Whether they do this intentionally I cannot say, and as for enjoyment, who can fathom the Molluscan Mind? But yes, this "surfing" behaviour has been reported, and I've seen similar.>
I thought he was ill and possibly dead the first time I saw him floating in the current, but he eventually landed on a surface, stuck to it and went about his business before finding another current. I think he might be a bit of a party animal.
<Some speculation that the Cephalopoda evolved from ancestors that did this, initially making short hops from rock to rock, but eventually becoming better at floating so they could go further, and finally learning how to swim through jet propulsion.>
Also, Speedy G has grown very quickly from his pinprick size. He's now approximately 1" x 1". Will Cichlids still eat or stress him at his size?
<Depends on the cichlid; some eat snails, shells and all, while others peck at soft wiggly things, including snail tentacles. These would definitely cause harm. But others ignore snails completely.>
I don't mind if they eat the baby snails.
<Indeed. Cheers, Neale.>
Here's some pictures of Speedy G current surfing and landing for reference.
<A very cute little snail. Ramshorns tend not to cause much harm in terms of breeding, but they are notorious plant-eaters. Likely a Planorbis species or similar. Cheers, Neale.>

Crooked Danio Baby 10/30/08
Dear WWM Crew,
<Hello!>
Hi, I am raising four baby Danio fish in a three gallon tank with a sponge filter and a heater.
The heater temperature set a 75 degrees. I feed them small meals three to four times a day and change the water once everyday.
<Sounds great.>
One of my baby Danio fish tail in the back seems to be crooked.
<Not uncommon with fish generally. The longer a species has been bred in captivity, which almost always means inbreeding, the more likely bad genes will surface. Nothing much you can do.>
The baby Danio fish that has the crooked spine is eating and swimming normally.
<May well remain fine, but often such fish have other problems as well and die sooner or later. It's your choice whether to destroy the fish or let nature take its course.>
I read that this can be a vitamin deficiency or a genetic problem.
<Can be either, but with "common" fish like Danios and Corydoras that have been bred for many generations in captivity, genetics is most likely the issue.>
If this is a vitamin deficiency what foods or vitamins can I give him/her to help overcome this deficiency?
<The damage is done; there isn't anything you can do. Next time around, you might decide to get parent fish from two or more stores, so that the odds of inbreeding are reduced.>
Thanks ahead of time for all your help. Jean
<Good luck, Neale.>

Zebra Danios don't look right 8/24/08
Dear Wet Web Guys:
<Coleen>
I have attached an image to show you how fat some of my zebra Danios have become, but these fish won't stay still for a photo and the lights not right. Sorry. It looks like the works of a Dutch Master.
<Hey!>
I initially thought this fish was "with eggs", but as she has remained big for months without change, I am wondering if she is less than healthy. Perhaps I have overfed her (and if so does she need a "diet"). I feed them Tetra Min flakes twice a day - only so much as they finish in 2 minutes. They don't really eat that much. (My growing female guppies in another tank can out eat them hands down on any day of the week).
<Mmmm...>
I am beginning to think it might be a more sinister problem - Is it possible that several things I have noticed are coming to suggest another problem?
<Is mostly a matter of diet here...>
Cracks in their skin: For example, I notice that larger of the six Danios I keep in this 10G tank have apparent cracks in their skin (especially underbelly).
Dark Spots: I have also just recently noticed several indistinct dark spots on the head of another fat girl. (I think they are girls, more silvery) I believe the spots are a new development for this particular fish as I have not noticed these before yesterday.
Tail ends drop down: Their tail end drops down when they pause from swimming.
Perhaps just aging? I don't think so: I wondered if my zebras might just be getting old, but I haven't had more than a year and they were all svelte when I bought them.
Tank set-up: Over the back filter which I turn off at night. Aerating with oxygen wand, no heater in tank. Central air in the house kept at 79. Aquarium planted with low-light plants and with substrate of laterite, 3mm gravel and Eco-complete and some Mopani driftwood. Using tap water treated with Tetra AquaSafe and tsp API aquarium salt per 10G with 1/3 water changes every week.
<Good practice>
Today's Quick Dip Test Results:
pH 6.2
KH 40 ppm
Cl 0 ppm
GH 75 ppm
Nitrite 0 ppm
Nitrate <20 ppm
Thank you for any insight you can provide regarding these problems.
Coleen
<I do think that simply changing their diet will result in slimming, improved health here. I encourage you to feed frozen/defrosted once per day (the AM likely) and the Tetra the evening meal. Brine shrimp or Daphnia are my choices for the bfast meals. Bob Fenner>

Dying Fish... Brachydanio 8/5/08
HI
I was trying to put out some of the stagnant water in my breeder's tank, and when I put it back into its suction I accidentally, partly crushed a Zebra Danio. He is now coughing upside down at the bottom of the tank. He is jerking around a bit. What should I do?
Sarah
<Hello Sarah. If the fish isn't dead yet, my assumption would be the physical damage is so severe recovery is unlikely. So if this appears to be the case, euthanasia is the only reasonable option.
http://www.wetwebmedia.com/euthanasiafaqs.htm
Cheers, Neale.>

Lumpy Danio
Hi Bob, <Don here today, Hi back>
We have a 10 gallon tank and have managed to keep 4 zebra Danios and one golden algae eater alive for 10 months. We have a carbon filter and change the filter every month. We perform water changes every 2-4 weeks (2 gals per time - treated with AquaSafe). We added a small aerator (bubbler) about six weeks ago. The bubbler is not adjustable so it runs
constantly and seems noisy. <Get a 3 way valve for the airline. Open the valve to the bubbler all the way. Close another. Open the third to slow the air flow to the bubbler. Adjust the blank valve until you get a good air flow. If it hisses, add a foot or so of airline as a muffler> Lights are on from 8 am to 8 pm daily. <Good>
Recently one Danio started developing a lump on its spine. Over the course of two weeks the Danio became listless and spent much time on the bottom of the tank. We removed him to a temporary place and tested the aquarium water. <Good to remove him. Is the spine bending? Or does it look like a small pea under the skin>
Temp 74 degrees <Ok, but 76 to 78 better>
Ammonia 0 <Great>
Nitrate 40 <Good, but a little high. Try to keep below 20ppm>
Nitrite 0 <Great>
Hardness 25 <Hard>
Alkalinity 300 (high) <Very>
pH 8.4 (high) <Very, very>
Do you know what the lump is? <Could be a tumor, in which case there is nothing to do. Sorry> Can the fish be saved? Right now he's sitting at the bottom of the temporary shelter, barely moving but still breathing. <This could be just about anything. I would try a good broad spectrum antibiotic. However, if the spine is bending the fish must be put down. Bury or put in trash. Do not flush. Wear gloves>
Is the pH or alkalinity to blame? <Could be. Danios will adapt to a wide range of water conditions, but yours are extreme. You could try peat moss in the filter. It will stain the water a rich tea color. Charcoal will remove the color> Should we take corrective action? <As above> Did the bubbler cause anything? <No>
Thanks,
Peg

Question: my Danio's tail is gone
Hello! I'm hoping you can help me. I noticed yesterday that one of my Danio's tail was mostly gone (long finned Danio). I have zebra Danios and plain Danios in my tank. I thought they were a non-aggressive fish so I didn't think that anyone else would've bitten his tail.
His spine doesn't look bent. He spends more time hiding in the foliage than he used to and seems a bit sensitive, but swims around with everyone some and eats fine.
Any ideas what is going on? The tail nubbin' looks healthy as far as I can tell.
< If the tail was not actually bitten off by a fellow tankmate then chances are that it was damaged and may have developed a bacterial infection that slowly ate it away. Do a 30 % water change, clean the filter and treat with Furanace to prevent any further damage.-Chuck>
Thank you so much!
Megan

Re: Question: my Danio's tail is gone
Thank you for the info. Can the Danio grow a new tail fin?
< If the damage is limited to the fin portion itself then it may grow back. If the damage has reached the caudal peduncle, The meaty portion of the tail then probably not.-Chuck>
Megan

Danio Problems
Hi,
I started off with 5 Zebra Danios and 4 Peppered Corys in a 70 litre tank and I'm now down to 2 Danios. About 5 months ago one of them got really bloated overnight and I found him the next day looking like his stomach had burst. Last week another one bloated up and then dropped dead within two days. Last night though, I noticed another one carrying what looked like a bruise on his side, he looked red beneath his skin then this morning he was dead on the substrate with what looked like two, small skin bubbles protruding from his underside. <Hi Dave, Don here. Two things come two mind. Let's hope it's a water quality issue. Do you check your water for ammonia, nitrite and nitrate? Any amount of the first two could be the cause. But, if you see any Danios showing a bend in their spine you have TB in your tank. If so, then the fish will have to be put down and the system sterilized. TB can spread to humans with a break in the skin. Be careful and wear gloves. There are also other bacterial infections that can cause this. If the spines are straight, try a good broad spectrum antibiotic. Oxytetracycline may help. Like I said, let's hope it a water quality issue>
I replace 5 <less than 10%> litres of the tank water every 7 days and the tank looks clean but there is obviously something going wrong somewhere.
Any advice would be more than appreciated as I really don't want the fish to suffer any more. <First thing I would do is test the water. If you see any ammonia or nitrite, or if nitrate is over 20ppm, fix it with large (50%+) water changes daily. I would also up your normal water changes to around 20 to 30%>
Thanks and best regards,
David

Danio Problems
Hi, Thanks for your advice. I have just been out to buy testing kits and will test the water quality when I have finished work this evening, I really hope it is poor water as the TB possibility terrifies me if I'm honest. How worried should I be for my own health, I know you say that it can enter humans via open wounds but what about just being around the tank, do you know if it becomes airborne? <No, it can't. I must enter through a break in the skin>
Also, do you know of any websites that you know of where I would find pictures of Zebra Danios with TB (curved spine etc). <Here's a link to my photos in our forum. Scroll down to the next to last pic. The two female White Clouds at the top of the photo show the bend pretty well. http://wetwebfotos.com/Home?actionRequest=userview&userID=4258 Some fish become very thin, mine bloated.>
Sorry if I seem to be panicking a little! <Understood. I really try to pass along the warning without causing any undo concern. I rarely succeed. Some say the bacteria is always present in our tanks, and that it takes a drop in the fish's immune system for it to show. If true, it would seem transmission to humans is rather rare. But some very respected people here suggest sterilization of the entire system whenever TB is found. That's a hard call to make, but harder to argue against. Let's hope it's the water. Don>
Thanks again,
David

Dying Danios
Hi, We've had our tank for about 3 months now. Among the second batch of fish we got were three Zebra Danios. All three have since died, one after the other. The first one experienced a bloating and a dullness of his color a few days before dying. Both the others seemed to waste away, becoming very thin over a period of about two weeks. All refused to eat after the symptoms set in. It took all three of them about a month and a half to die total. All the other fish in the tank seem to be doing fine. Is this something that we should be concerned about either for the other fish or for ourselves, or was this just a "bad batch" of fish?
-Greg
<Hi Greg, Don here. I do think you got a batch of bad fish. The question is bad with what? They had some sort of internal infection. It could have been anything from bacteria, protozoa, even worms. Knowing what type of infection it was would set the risk to the other fish and yourself. If the Danios spines curved as they wasted away then they had fish TB, which humans can catch through breaks in the skin. I would just watch the others at this point. If any more get thin, email us back with details>

Hunchback Danio
I am a fairly new aquarium hobbyist (1 year) and keep having a problem with "hunchback" Danios in my one of my tanks. <Not good> The tank in question is a small Eclipse Hexagonal 5 gallon with a small pebble base, plastic rock formations and a couple of small live plants that was cycled about 4 months ago. There are currently 3 Zebra Danios, a Chinese Algae Eater and many small snails (from the live plants) in the tank. My current readings are Ammonia 0, pH 7.0, Nitrite at 0 and Nitrate is 20. <Thanks for testing your water and sharing the results. But not the problem here.> I have had two other Danios run through the same symptoms as the current one, hunched back, decreased size, hover at the top of the tank, don't play with the other fish, don't eat and then finally end up as floaters that get flushed.
I would like to avoid flushing anymore of the little guys if at all possible, symptoms just started a few days ago, can you help?
Shelly
<Hi Shelly, Don here. I saw where you posted this in our forum and strongly agree with Steve and others that this is a situation where the fish should be put down safely. The hunchback Danios have TB that can spread to humans. I know it's hard, but this is one of those times that as responsible pet owners we must act in order to keep ourselves and our other fish safe.>

Humpback Danios
I did not explain correctly on the bio-filter, it is a bio-wheel. Can it be sterilized? <Yes. Soak it in a bleach solution then rinse well and soak in dechlorinator. Good to go. Boiling would also work, but may warp the wheel. Don>
Shelly

Humpback Danios
Okay, I think I have come to the realization that I need to put my good little fish down and sterilize the tank but one more question. This tank has a bio-filter; do I need to get rid of it too? <No need to throw it away, but it must be sterilized like the tank. You will need to recycle it. Just refill it and throw in a small cocktail shrimp or a pinch of food. When both ammonia and nitrite have spiked and crashed you're good to go. Figure 3 to 6 weeks. Don>
Shelly

I need help fast for my zebra Danio
I'm not really sure what the problem is.
<Sabrina here, to try and help>
He or she, I can't tell, has just over the past few days shown any of the listed symptoms. swollen belly, hunchback tail, head pointed upward, won't eat, but he swims normal hangs out at the top with the rest of the zebras.
<Hmm, this isn't a lot to go off.... Can you give us some more specs about your tank? How big is the tank? What other fish are in with the Danio? Do you test your water for pH, ammonia, nitrite, and nitrate? If so, can you let us know the values? What you describe could be a number of things, but what sticks out most to me is the swollen belly - are his scales sticking out, pinecone fashion? I'm afraid you *might* be dealing with dropsy, which is extremely difficult to cure at best, but perhaps there are other possibilities, too. Let us know more about your tank, and we'll be more able to help you figure out what's wrong.>
Thank you for your time.
<No problem - I wish you the best.>

Zebra Danio with strange caudal fin 1/16/06
Hello there! I've been breeding zebra Danios for a while, and recently, after my fry matured into full grown adults, I noticed that a few of them have a different colored caudal fin. All them, except these few, have the lines going through their body, go into the fin, ending when the fin stops. However, for these few, it stops where this fin is attached to the body, and on the fin, it has blotches of like black lines and black dots all mixed up on the tail randomly, that really sticks out, and sort of reminds me of a guppies tail. I tried to take pictures so I could attach it to this, to show you what i mean, but i couldn't get the camera to focus on the Danio and everything kept coming out blurry and unfocused so you couldn't really tell what was going on. I looked all over the net but i couldn't find anything about Zebra Danios with tail fins like this, and I thought this might be something new going on, because I've never seen any other Danios like this before until now. What do
you think?
Thanks, Tyler Ross
<Mmm, likely just part of the randomness of genetic mix... This is how the vast majority of sport mutations are "developed"... e.g. long tails... Bob Fenner>

Zebra Danios With TB 12/05/2005
Hi, We have 10 gallon tank and have started the tank 4 months from now. We bought 3 Danios to start with, and they did very well for first 2.5-3 months. We used to do weekly water change. Our local pet store suggested to not to change water for first month to have fully cycled tank. We stopped the water change. I am not sure if this is the cause or something else, but we lost our smallest fish during this time. Rest two fishes has lived fine for some time and they started slowing down. They used to eat a lot and swim around in whole tank that is filled with natural plants. They stopped eating with that eagerness. They stopped playing. We noticed that their spine is also got curved.
First we were thinking that they are getting old. After reading FAQ section in your website, we are scared about fish TB. I have been touching the water to clean up the tank. Though I don't have any wounds, but still I am scared and wanted to know what measure we can take to diagnose if we got infected or not.
About the fishes, now they both are dull and during the night they lie down on the bottom of tank. Actually till light is off mostly they lie down on the bottom. If light is on, they try to swim. We can see they have hard time swimming. They most stand still at one place. I have also read on internet somewhere that when they are at the end of their life cycle, then also they develop curve in their spine. So how do I know if my fishes have TB or they are just old.
In summary these are questions I have.
1) What measures can we take to find out if we have infected ourselves with the fish TB?
< Fish TB is very very rare. If people were getting infected and it was a problem I think you would see warnings all over the place. As a precaution I just wash up after having my hands in an aquarium.>
<Rare in people, yes.... but I have seen many, many cases in fish lately - many of which were Betta splendens.... -SCF>
2) how do I find out if my fish's spine is getting curved because they are old or they have fish TB?
< More than likely your fish are getting old. Usually these little guys don't last more than a couple of years tops and the contouring of the spine is one of the signs of a fish getting older.>
3) In case of fish TB, how do I sterilize the whole tank? Do we have to start from scratch for the new fishes?

Danio with bubble-like growth 4/3/06
Hey Crew. My zebra Danio has recently developed a small, bubble-like growth on it's bottom lip. I've had this fish for a just over a month, and this has developed perhaps within the last week or so... just after the fish was added to the main tank. I would have liked to attach a picture, but I'm sure you know how difficult it is to get a zebra Danio to sit still. The bubble is grey/clear in colour, and probably about 1mm in diameter. I'm fairly sure it's not ich, as it isn't white and has a well-defined round shape. The fish is otherwise swimming, eating, and behaving normally.
<A good clue... very likely this is "just resultant from a bump">
Here's the data on this fish's environment: 20 gal. tank with live plants, heated to 23-24c. Tankmates are two other zebra Danios, two dwarf Otos, and four Cory cats, all healthy. The tank is cycled, readings are ammonia 0, nitrite 0, nitrate approx. 15 ppm, pH stable at 8.0-8.1.
<A bit high...>
In my own research to determine what this growth is, I saw references to lip fibroma, but I only read of it occurring in angel fish. Could this be what's afflicting my Danio, or is something else afoot in my tank?
<Could be an "oma", tumorous... but doubtful here... And assuredly nothing one can treat... nor would I risk excising it. Likely will "go" of its own accord. Bob Fenner>
As always, thanks in advance for any help you can offer. JM

Wasting symptoms in Zebra Danio 3/15/06
Hello,
<Sharon>
I had a 30L freshwater BiOrb containing 3 White Cloud Minnows, 2 Zebra Danios and a living plant.
Water condition is good - Ammonia 0, Nitrates 0, Nitrites 0 and pH 7.6.
About 6 weeks ago I lost one of the Minnows. Symptoms included enlarged abdomen (I initially thought it may have been pregnant) followed by (48 hours before death) bent spine, floating near surface and lack of appetite.
In recent weeks I have noticed:
* one of the Danios appears to be wasting away i.e. is very skinny (although it is still eating normally and active),
* one of the Minnows appears to have an enlarged abdomen (also eating normally and active).
I lost a second Minnow last night - not the one with the enlarged abdomen. I had been away for a couple of days and returned to find it with looking skinny with a bent spine. It also had swim difficulties (probably due to bent spine), lack of appetite and was floating near surface. I quarantined it immediately in salt water, but to no avail.
I have searched your website and come to the conclusion that my fish may have either an internal parasite (bad) or TB (really bad). What do you think?
<Could be... perhaps from just "initial" troubles (you bought them with this)... But could be environmental to a large extent... or nutritional. What do you feed your fishes?>
And, if you could provide some advise for on my next course of action that would be much appreciated?
Regards,
Sharon Bell.
<Mmm, I would ask your stockist/LFS if they've been having trouble with their minnow fishes... You can/could become involved in sequential antimicrobial "trials"... in the hope of blocking something at play here. My first choice would be a Furan compound (likely Furanace). Bob Fenner>

Re: Wasting symptoms in Zebra Danio 3/17/06
Hi Bob,
<Sharon>
Thanks for the speedy reply.
<Welcome>
I just wanted to let you know that I didn't buy the fish with the BiOrb. I set the BiOrb up about 9 months ago initially (unsuccessfully) with a couple of small fancy goldfish.

The Danios and minnows were purchased and added to the tank 3-4 months ago - after a 75% water (de-chlorinated) change, a thorough cleaning of the BiOrb and making sure that the BiOrb had cycled.
I feed them frozen daphnia, frozen bloodworms, flake food (left over from the goldfish - but I did compare the ingredients with those of the other fish foods available) and boiled peas. If I go away, I leave them a sinking pellet (Spirulina rich) to nibble on.
<Should be fine>
I do a 25% water (de-chlorinated) change fortnightly, and change my filter quarterly - whether it's dirty or not. (The Danios and minnows are much cleaner than the goldfish were!)
<Yes>
I live in Australia and haven't been able to find anything containing a furan compound.
Also, what did you mean by antimicrobial trials? And, how would I carry those out?
<Mmm... there are a goodly number of "broad spectrum, gram-negative antibiotics" sold for pet-fish use... And as hinted, the "search" for one that is efficacious here is a matter of trial/s... I would use (serially) what you can find... at a/the stock dosage of 250 mg./ten gallons system water... three times, three day intervals... with water changes between>
I will ask my LFS if they have had any trouble with their minnows this
weekend, but in the meantime is there anything else you suggest?
Regards,
Sharon.
<Mmm, the application of Epsom salt here might act as a temporary cathartic. Bob Fenner>

Minnow behaviour & health 10/3/06
Hi
<Hello there Charlotte>
I have four pairs of minnows (2 zebra Danios, 2 coldwater, 2 long fin and 2 yellow ones: apologies for the lack of description by proper name but I can't remember).
<Perhaps a small journal you can keep...>
 They all get along quite happily with four fancy goldfish and a coldwater Plec and all seem in general good health, having joined the goldfish approx 6 months' ago.
On Sunday, I purchased 3 very tiny fantails (one smaller than the zebra minnows!) and all seem well. Today I have noticed that the yellow and long-fin minnows seem to be displaying to each other by opening their fins wide and synchronized swimming! I have been trawling the internet and my books but none give any indication as to what this behaviour means.
<Perhaps reproductive behavior... maybe just dominance displays>
Is it possible that it's due to the slightly reduced territory now there are 3 new fantails (albeit very small ones) or is it a breeding thing (one of the yellow ones looks a bit portly)?
<How large is this system?>
As a secondary point, on reading various articles relating to minnows I noticed in one of yours reference is made to a bent spine indicating TB infection.
<One possible cause of several... covered on WWM.>
This concerns me as one minnow has a very bent spine. He's always looked like this, has grown well since purchase, as have all the other fish. As mentioned above, all of the fish in the tank seem in general good health and water quality is fine. Should I be concerned about TB or do I just have a minnow with a wonky back?
Your comments would be greatly appreciated.
Many thanks,
Charlotte
<Please read here: http://www.wetwebmedia.com/FWSubWebIndex/gldfshsystems.htm
You may need more room, less fish livestock. Bob Fenner>

Zebra Danio with growth? on side 9/23/07
Hi,
I have an approx 35-40 gallon tank-it's one of the tall 6 sided ones. I inherited it from a business I purchased a little over a year ago, and ended up moving it to my house. It came with a few swordtails, and I added 3 zebra Danios about a year ago. Two swordtails died three or four months ago, I had calculated they were at least 2 years old, and possibly as old as 4 according to an employee so I assumed it was due to old age. There was 1 swordtail left and the 3 Danios, and we added 3 Cory cats. Nothing else has been added in the last 3 or 4 months. There's a hang-on filter as well as a long airstone in the bottom, and there's a really thick gravel layer. I vacuum the gravel and do about a 30% water change every few weeks- I know it's pretty lightly stocked so confess I haven't been too terribly obsessive about this. I have not added more fish as I have been pretty busy and didn't want to upset the balance in the tank as everyone had been settled a while.
Last week, the last remaining swordtail died. I know she was only about a year old as she was a baby when I inherited the aquarium.
She acted fine, then one day I noticed her hiding in the plants, (plastic plants) next morning was dead.
Last night, I noticed one of the Danios has a horrible growth? sore?
something on his side. It looks for all the world like his intestines are spilling out of his side. Last night it was red with a white spot on the top, like a pimple. Today the white spot is gone. He was swimming and schooling normally last night, but today is at the bottom in the plants, hiding. The other fish are acting fine.
Please advise on how I should try to treat him-is it some sort of parasite? I tried all sorts of searches but couldn't find anything. I don't have a quarantine tank or extra filter but could put him in a bowl, or something similar.
Sarah
<Sarah, without a picture it is impossible to safely identify this disease or problem. From the sounds of things -- where you are seeing internal organs pushed against the skin -- it sounds like a tumour or cyst of some sort. These are relatively uncommon in aquarium fish, and there causes are various. There is no cure, and generally the best situation with very small fish (like Danios) is to painlessly destroy the fish. Large fish, such as big cichlids and Koi, can sometimes be treated by a vet, either through surgery or via drugs. Now, this isn't to say that destroying the fish is the end of the story. Whenever fish sicken or die within a short space of time, you need to wheel out the nitrite and pH test kits. Use the nitrite test kit to make sure the filter is working properly. If the nitrite level is anything other than 0, you have a problem. Likewise, the pH test kit will reveal if the water chemistry is stable. For the collection of fish you have, the ideal pH is around 7.5, and more specifically you want moderately hard water as well. Also, you might consider increasing the water changes. A good level is 50% weekly, though if the tank is understocked, you might be okay with 25% weekly. Cheers, Neale>

Update-Zebra Danio with growth PICTURES 9/23/07
These 2 pictures show the growth on the Danio- the first one you can see how it protruded. The second one, only about an hour later, is of the dead fish- it was stuck to the water intake on the growth side, and the growth was no longer protruding and looked like the skin was rubbed off, but you can see the size/position. (I do have bigger pictures, if needed.)
<Definitely a tumour of some sort. No cure in a fish this size. Can be caused by any number of different things. Concentrate on check water quality and chemistry, and then acting accordingly. Cheers, Neale>

Update: Zebra Danio with growth 9/23/07
Hello,
<Hello,>
I sent a question earlier today regarding my zebra Danio with a growth on its side-it had some details about the problem, and the history of my tank (acquired as part of a business purchase.)
Unfortunately, the Danio has died. One moment it was schooling and I was trying to take pictures, I came back and it was dead and stuck to the water intake. I have taken several pictures which I am sending in a separate e-mail, as I am still wondering what this was and what caused it, and I am worried about my other fish as I seem to have more problems.
<Ah well, nature took its course there...>
I wanted to give a bit more info as I was in a hurry earlier. After e-mailing you, I did about a 20% water change-I replaced 9 gallons.
My standard procedure involves mixing the tap water with a dechlorinator in a 3- gallon bucket, then adding slowly to the aquarium in case of temp variations. I used Stress Coat by Aquarium Pharmaceuticals. I have 3 gallons marked on the bucket and added 3 ml of product to each bucket, as directed on the product for stressed fish. (is this a suitable product, btw? I noticed your article talking about "real" dechlorinators but not sure how to tell which is which.)
<They're all "real", but the question is whether or not your dechlorinator removes chloramine as well. Some do, some don't. If your local water board puts chloramine into the water (not all of them do) then adding a standard dechlorinator without chloramine remover results in high levels of ammonia. This ammonia is toxic to the fish. 'Stress Coat' has chloramine remover, so should be fine.>
I have a hang-on "Aqua Tech 20-40" filter, and also replaced the filter cartridge (not the biological medium, just the carbon filter.)
<I'd bin the carbon, and add more biological filter media. Carbon is redundant in most freshwater tanks, and is a positive risk in some ways, because it removes medications.>
I added new water slowly to minimize any temp variations. I usually match the new water temp to the existing water temp by the decidedly low-tech method of "feeling."
<It doesn't really matter too much if the new water is cold. Provided the water temperature difference is a few degrees C, the fish couldn't care less, and some, like Danios and Corydoras, actually like swimming into cold water.>
I noticed the water in the aquarium seemed awfully warm, but thought that since the heater had turned on I must have been mistaken. I little later, I noticed the heater still on. On a whim, I pulled out my candy thermometer and found the aquarium water was between 85 and 90 degrees. I unplugged the evidently malfunctioning heater, which was set to the lowest heat level.
<This happens from time to time. One approach that works well is to use two slightly too small heaters instead of one. For example, if your tank needs a 100 W heater, use two 50 W heaters instead. This way, if one sticks in the on position it cannot "boil" the fish because it is too weak to heat the tank dangerously high. The other heater will switch off normally. All this said, modern heaters from reputable manufacturers tend to be very reliable.>
I know that the water I added was slightly cooler than the existing aquarium water, so there is no telling how long this thing has not been working right and I am wondering if the hotter water was the reason I lost my swordtail.
<Possible, but unlikely. Generally extremes of temperature cause obvious problems first: if too hot, the fish gasp at the surface, if too cold, they become lethargic and off their food.>
I had noticed the heater seemed to be on a lot, but I was not really sure how warm they needed the water to be and as the heater was relatively new and was supposed to automatically regulate the temp, I assumed all was well.
The fish were all acting fine, and were not gasping at the top or acting distressed- the Corys happily scavenging and the Danios hanging out near the top.
<Very good.>
About an hour later, I went to check again, and one of the Corys was dead, just laying upside down on the bottom.
<Curious. At this stage, I'd be whipping out the nitrite test kit.>
Now I am wondering if I inadvertently caused the death by unplugging the heater and causing a rapid temp drop, but I was afraid of how high the temp would go. The candy thermometer says the temp is 85 now. I also can't figure out if something went wrong at the water change, although I used the same bucket and did everything as I always do.
<Water doesn't tend to rapidly cool down or warm up, and Corydoras in particular have quite a high tolerance for extremes, at least in the short term. They are air breathers, so able to tolerate warm water, and the common species (peppered and bronze Corydoras) are subtropical fish that can tolerate cold water for weeks at a time in the wild.>
Right now the heater is still off. The Danios seem agitated, although I may just be nervous.
<Again, Danios are subtropical fish, and generally tolerant of cold water for short periods. So lack of heat, unless the room is very cold, shouldn't be an issue.>
I am out of water test kits- I tested frequently when I added the Cory cats about 3 or 4 months ago to make sure of no spike, but haven't tested recently As I inherited the tank after it had been established for years, and have only added a couple fish, I have never had a reading over 0 on ammonia or Nitrite, and Nitrates have always been under 10.
<That was then, this is now... do the water tests. Nitrite and pH are essential here, as both are good indicators of background changes.>
I should mention I consider myself a complete newbie. Although I've had this tank about a year I have not really added many fish, basically just doing water changes and letting it be. I added the hang on filter, the airstone, and the heater, it had none of the above. There was an existing undergravel filter but I realized that it did not seem to be properly set up- it was just a loose tube from an air pump pushed down into the tall tube without being connected to anything, and I wasn't sure how to fix it. (please excuse my technical terms.)
<Hmm... normally their is a transparent vertical tube a few cm in diameter in one corner of the aquarium. This is connected to a filter plate underneath the gravel. An airstone is placed at the bottom of the vertical tube. As the bubbles rise, they pull water up the vertical tube, and this up-flow of water draws water into the undergravel filter. While considered "old fashioned" nowadays, a properly maintained undergravel filter works very well. It is possible by disconnecting the undergravel filter you've reduced filtration capacity below that needed for your aquarium. Without an undergravel filter, you need an external or internal filter that generates turnover of not less than 4 times the volume of the tank. So if, for example, your aquarium holds 100 litres, the filter should be rated at 400 litres per hour.>
I wanted to take the time to do more research before really getting into adding fish, etc, as I didn't want to rush in and kill anything, and have been too busy to do much with it. I have had the David Boruchowitz Freshwater Aquariums book for a long time, well before I had this tank, and had wanted a tank a long time but never took the plunge. The book is great, and has lots of advice for getting started the right way, but not really anything about what to do if you run into a problem.
<Ah, well, maybe WWM can help out here!>
Anyway, if you can, please let me know:
1. If the growth seems to be some sort of parasite I should worry about, or something individual to the fish.
<Not a parasite.>
2. Is the death of my swordtails related to this recent death?
<Quite possibly; if conditions are "bad", fish may all die from different diseases but were ultimately connected to the same cause.>
3. Was the high water temp likely the cause of all the problems?
<Possible, but unlikely. Unless the water went about 30 C, there shouldn't be any immediate risk to your fish. That said, the ideal temperature for your collection of fish is around 24 C, given you have a mix of tropical and subtropical species.>
4. Do I need a new heater with the fish that I have?
<Well, you need a heater, yes.>
I live in the Houston, Texas area. It stays pretty hot, so the AC runs almost year round. My house is pretty much a constant 77. I had been keeping the top off the aquarium as a lot of sun comes in the windows and I didn't want it to get too hot. I was reading the online article about the sub-tropical aquarium, with no heater- would this be a good choice for me?
<Depends on the fish. Even in subtropical climate zones, having a heater set to its minimum setting is a good idea. During the summer here in England, I turn the heaters down to 18 C. This way, the fish get the nice, natural variation in temperature they prefer, but I get the peace of mind of knowing if there's an unseasonably cold night, the fish will be fine.>
Of course, I'm adding nothing until I've figured out what the problem is now. I just have 2 Cory cats and 2 zebra Danios left, would they be OK with that kind of setup?
<What kind of set-up? A subtropical one? You appear to have zebra Danios (Danio rerio) and three-line Corys (Corydoras trilineatus). Both of these will tolerate fairly cool water quite well, though only Danio rerio is truly a subtropical fish. I'd recommend adding a heater but setting it to slightly below normal, around 24 C. Most of the time the heater will stay off, given where you live, but it'll come on during the colder times of the year.>
I basically want something with fairly hardy fish, as my kids get pretty attached to them. I'd like to add some more Cory cats- maybe a total number of 6, and another 2 zebra Danios. Then I am assuming I can add one more small school - what would be a good choice- I was looking at perhaps 3 or 4 white clouds, although my young daughter would like serpae tetras.
<Research your fish carefully. Corydoras and Danios work best when kept in large groups of their own species. In the case of Corys, they school nicely and become much mess shy and nervous. In the case of Danios, you don't get so much fighting between the males. Serpae tetras should be avoided if possible because they are notorious fin-nippers, and Corydoras seem to be prime targets for nippy fish. White Clouds, on the other hand, are good subtropical fish and would do well at 24 C. They do tend to get bullied by the slightly larger and more boisterous Danios though, so approach this combination with caution.>
As it is one of those annoying tall aquariums, and the Danios hang out at the top and Corys hang out at the bottom, perhaps you could recommend something that would like the middle ranges.
<To be honest, my first call would be to swap the tank for another if you can. Choosing fish for a tall tank is throwing good money after bad: tall tanks hold fewer fish than long ones (because of surface area at the top for gaseous exchange) and schooling fish especially don't enjoy the limited swimming space. You can obviously re-use the filter, heater, etc in a new aquarium. But if this isn't an option, then perhaps your best bet would be paradise fish (Macropodus spp.). While the males are aggressive (so only get one, or none at all) the females are harmless enough. They are classic subtropical fish, and when mature have beautiful colours: blue and red stripes.>
Thanks for your assistance, I've been reading quite a while and enjoy it.
Sarah
<Hope this helps, Neale>

My ever-dwindling Danio population (Danio Illnesses) 12/23/07
Hello out there in the wonderful world of Wet Web Media,
<Brian>
I am writing out of a combination of consternation and desperation. I am new to fishkeeping (February 14 will be my one-year anniversary) and I have two tanks: one is a twenty-nine gallon planted tank and the other is a ten gallon planted tank. In this post, I am writing about the twenty-nine gallon tank.
First, a little background... My tank is about eight months old and I added fish slowly (though I might add, without quarantining - that is what the second tank is for, but I bought it mid-way through stocking the first one). My ammonia and nitrite are both zero. My nitrate is greater than
20ppm but less than 40ppm
<Both too high...>
(hard to tell with the color based tests). I do a 25% (about 5 gallons which is 25% since there is only about 25 gallons of water in the tank accounting for the displacement from the substrate, rocks, wood, and plants) water change once a week. I do NOT use a C02 machine, but I do put in Excel (one capful) every other day.

The plants in the tank include: a ton of Blyxa japonica, a hearty Anubias, two flourishing (melon?) swords, crypt spatulata, java moss, and Myrio which grows like weeds. The non-fish fauna in the tank include: Amano shrimp (2 males, 1 female), 5 cherry red shrimp (and about 20 babies across three generations), and green shrimp (not sure how many because they hide, but at least one no more than four) and various snails. The fish in the tank include: one Bristlenose Pleco (sans bristles - grumble!), two honey dwarf Gouramis (one definitely male, one either female or passive male); one flame dwarf Gourami, one Oto negro, one Siamese algae eater (too big for its britches - not sure what to do with this voracious eater),
<Keep your eye on... move if too aggressive>
one pregnant female platy (who has never once -visibly- given birth but is a fat blimp), one chocolate Gourami (named chip, short for "chocolate chip"), and two male rainbowfish (dwarf praecox), one zebra Danio and one leopard Danio.
So here's the problem. My tank population has recently dwindled. In the last two weeks, I have lost two zebra Danios. About a month before that I also lost a zebra Danio (when I started my tank I had four). About four months ago, my fattest (alpha?) female Danio seemed to get sick - her spine started to curve and she was "hiccupping", having these strange convulsions that looked like she had a neurological disorder. Over the weeks, she got progressively worse until she was swimming funny (she almost seemed like she was no longer buoyant - she kept sinking and was swimming in this weird diagonal pattern). I tried to look it up online (even on this site) and from what I could glean - the fish was constipated. The cure seemed to be quarantine and no food for 2 days. After six hours in the quarantine tank she seemed improved and after three days, I returned her to the main tank.
She was fine for about six weeks and then she died.
Four weeks later, one of my Danios had a pinkish sore on its side. I am not sure but I think it was "missing a scale" (not even sure if this possible, but it is my best estimation). About two weeks later, I came home and a different zebra Danio was dead (at the bottom of the tank) and the one with the sore, well it was ... well, I am not sure how to describe it. It looked as thought it was being eaten alive. One side of its body it was fine and silvery and the other side was raw - pink/red as though someone had been munching on it. Oddly enough, the fish was swimming around just fine, but it looked nasty. I put it in one my larger fish nets (I know not the best idea, but it was a contingency plan) and tried to isolate it from the other fish after I found my dwarf flame Gourami trying to nip at it. Sadly, the Danio didn't make it.
Two days ago, I came home and my leopard Danio was swimming at an angle and well... I also don't know how to describe this but it looked like had exploded. Pardon the description - from the front and sides it looked fine but most of the bottom 1/6 of the fish was ... well gone and looked pink and fleshy. If it were possible for a fish to "explode" from eating too much, this is what I would hazard it would look like. The good news is that after two days, the fish is still alive (not visibly being harassed by other fish ... ) and seems to be healing. The fleshy part has actually gone from a reddish pink to a paler pink. It looks less like it is "throbbing".
Now that you have heard my story, here are my questions:
1. Does this sounds at all like "whirling disease"? I just started reading about this (by the way, your link to www.fishdiseases.net on the whirling disease FAQ is broken)
<Does read as some sort of internal bacterial complaint... particular to Cyprinids...>
2. If not, what does it sound like? I have not had any luck finding anything that fits these symptoms (if they are all related).
3. What do I do? Are my other animals in danger?
<I would skip using Danios and their relatives in this system... Really. Not worth trying to treat, remedy here. The list of other livestock... that is more sensitive to general areas of poisoning let's say, is telling>
I am not sure if you can tell from my post, but I have taken being a fishkeeper really seriously.
<Yes... you 'read' as a very earnest individual of intelligence, tenacity>
I have been reading a ton (subscribe to two fishkeeping magazines, read this site, joined my local aquatic plant society). Every time a fish or other animal dies (3 Otos, 1 bamboo shrimp, 1 white dwarf Gourami, 1 bumble bee goby [which would have done better in a brackish environment, I found out after] and 2 female Amanos), I spend hours trying to figure out why they die. My water is clean, my nitrogen cycle is fine, I feed regularly, and my plants are thriving. Any help would be useful.
<As stated... many Danios perish "consequent" to the conditions in which they were reared in the Far East...>
4. I read somewhere that if a fish has whirling disease, the fish should not be flushed. ACK! I didn't realize that - is that true for all dead fish? I am a city boy and I don't really have a "plant" to bury the fish in. Can you please give me some suggestion for appropriate means of disposing dead fish?
<Best to freeze all in a plastic bag... toss out with solid trash service>
Sorry for the long post. I look forward to your reply.
Brian in San Francisco
<Bob Fenner in Key West>

Question re: TB, and Fin damage - 4/3/08
Good day,
First off I want to thank you all for this extremely valuable resource for us fishkeepers and your time and knowledge- You have saved a many of fish I assure you.
Couple questions: In my 100 gallon main tank I have 4 Bala sharks that are still fairly young. The tank is cycled with Am-0 ,nitrite-0, nitrate-10- There are lots of Amazon sword plants and a few other plants I am not sure of. All except one of the Bala's have either frayed or split fins but are otherwise very healthy and growing fast. Should I be concerned or should I just keep a watchful eye on them? The one with fins intact seems to have a belly unlike the others so I don't know if they are squabbling over "her " or what. Some of my other inhabitants can be fin nippers so I realize that this is not the only possibility.
My next question involves Goldfish (a.k.a zebra Danios) I went to my dads last night (not the best fishkeeper) and I saw that his Goldfish was sort of floating vertically, listlessly. Not only that but he has a definite "bump" or hunched back (see attached pic, hopefully you can see it) I am not sure of his water parameters but I snatched him, brought him to my house and put him in my QT tank so my dad wouldn't flush him. After researching I have concluded that it could be either be TB or just old age (even though I don't think he's more than a year old but one "expert" stated that Danio's can get a hunch back just as they age (I don't know how reliable they are) Well, immediately after getting into my QT tank he has perked up and is swimming around and everything...He "acts" like he is eating but I honestly think he is just spitting it back out- its hard to say for sure. Do you think it is indeed TB and if so, exactly how do I disinfect my tank after
he "succumbs" and what do you recommend as an ideal method for Euthanization (I realize everyone has their own opinions but I am looking for the easiest for both me and the fishy) I am nervous about using bleach to disinfect the tank because when I was a young'n I did and I guess I didn't rinse well enough because it killed all of my fish immediately :(-
Lastly, (I know, sorry this is a lot) About two weeks ago I had a big oops. In my QT tank (at the time had 5 Neons and one female Pregnant guppy) I was stupid and decided to buy the cheapest heater there was. Well, little did I know there was absolutely NO safety feature on this thing whatsoever. I plugged it in and fell asleep woke up an hour later and the thermometer read 115 F !!!... Amazingly only 2 of the Neons and possibly the fry in "utero" didn't make it. In my frenzy I decided to forgo the "gradual" temp change rule and kept putting ice directly into the tank until it was WNL. Well, the second the ice started melting the lifeless fish that were laying on the bottom perked up and swam to the top to get more so I couldn't deny them. ANYWAYS- My question here is this: I know that this stress could very well open the doors to many of illnesses and now 2 of the surviving Neons have white areas on their body's that are opaque and
completely block the "neon" and all color. Is this "neon tetra" disease or something else and how do I handle it? FYI I will never buy such useless and dangerous equipment again- I assure you.
One more thing I promise....A month or so ago, I emailed in with problems regarding Dwarf Gourami's- I was told that it was probably DGD and it would be best to put them down. I did lose 2 but on the third I decided to try something. He had all the symptoms of DGD BUT the lesions. Well, I treated with Parasite Clear for 4 days (it took two treatments to see results, I thought he was dead many times) a few weeks later he is better than he has ever been!! Has tons of energy and eats like a pig. I just thought that this might be helpful and others might be able to try this if they suspect DGD but want to try and save their pets.
Again, thank you all for all that you do and please know that I (as I am sure others) are extremely grateful for every second you devote to helping.
Very Respectfully,
Grace

question re: TB, and Fin damage - 4/3/08
Good day,
First off I want to thank you all for this extremely valuable resource for us fishkeepers and your time and knowledge- You have saved a many of fish I assure you.
Couple questions: In my 100 gallon main tank I have 4 Bala sharks that are still fairly young. The tank is cycled with Am-0 ,nitrite-0, nitrate-10- There are lots of Amazon sword plants and a few other plants I am not sure of. All except one of the Bala's have either frayed or split fins but are otherwise very healthy and growing fast. Should I be concerned or should I just keep a watchful eye on them?
<Yes, be worried. Either Finrot (caused by poor water quality, regardless of what your test kits say) or physical damage (fighting/fin-nipping). Treat with anti-Finrot medication, e.g.. Maracyn or eSHa 2000, but not Melafix or "tonic salt".>
The one with fins intact seems to have a belly unlike the others so I don't know if they are squabbling over "her " or what. Some of my other inhabitants can be fin nippers so I realize that this is not the only possibility.
<Remove the fin-nippers to another tank.>
My next question involves Goldfish (a.k.a zebra Danios) I went to my dads last night (not the best fishkeeper) and I saw that his Goldfish was sort of floating vertically, listlessly. Not only that but he has a definite "bump" or hunched back (see attached pic, hopefully you can see it) I am not sure of his water parameters but I snatched him, brought him to my house and put him in my QT tank so my dad wouldn't flush him. After researching I have concluded that it could be either be TB or just old age (even though I don't think he's more than a year old but one "expert" stated that Danio's can get a hunch back just as they age (I don't know how reliable they are)
<One year isn't "old" for a Danio. They easily live for 3+ years when properly cared for.>
Well, immediately after getting into my QT tank he has perked up and is swimming around and everything...He "acts" like he is eating but I honestly think he is just spitting it back out- its hard to say for sure. Do you think it is indeed TB
<Unlikely; quite rare in freshwater fish. I'd simply feed him up and see how he does. Nothing to lose. If he gets fatter and healthier, then he'll be fine; if not, painlessly destroy.>
and if so, exactly how do I disinfect my tank after he "succumbs"
<Clean and air dry the hospital tank.>
and what do you recommend as an ideal method for Euthanization (I realize everyone has their own opinions but I am looking for the easiest for both me and the fishy) I am nervous about using bleach to disinfect the tank because when I was a young'n I did and I guess I didn't rinse well enough because it killed all of my fish immediately :(-
<See here:
http://www.wetwebmedia.com/euthanasiafaqs.htm
>
Lastly, (I know, sorry this is a lot) About two weeks ago I had a big oops. In my QT tank (at the time had 5 Neons and one female Pregnant guppy) I was stupid and decided to buy the cheapest heater there was. Well, little did I know there was absolutely NO safety feature on this thing whatsoever. I plugged it in and fell asleep woke up an hour later and the thermometer read 115 F !!!... Amazingly only 2 of the Neons and possibly the fry in "utero" didn't make it. In my frenzy I decided to forgo the "gradual" temp change rule and kept putting ice directly into the tank until it was WNL. Well, the second the ice started melting the lifeless fish that were laying on the bottom perked up and swam to the top to get more so I couldn't deny them. ANYWAYS- My question here is this: I know that this stress could very well open the doors to many of illnesses and now 2 of the surviving Neons have white areas on their body's that are opaque and completely block the "neon" and all color. Is this "neon tetra" disease or something else and how do I handle it? FYI I will never buy such useless and dangerous equipment again- I assure you.
<Observe for a while before deciding this is Neon Tetra Disease; stressed Neons will indeed lose their colour. But Neons with NTD also lose weight and become strangely shy, separating off from their school. NTD is unfortunately not curable.>
One more thing I promise....A month or so ago, I emailed in with problems regarding Dwarf Gourami's- I was told that it was probably DGD and it would be best to put them down. I did lose 2 but on the third I decided to try something. He had all the symptoms of DGD BUT the lesions.
<In that case, not DGD!>
Well, I treated with Parasite Clear for 4 days (it took two treatments to see results, I thought he was dead many times) a few weeks later he is better than he has ever been!! Has tons of energy and eats like a pig. I just thought that this might be helpful and others might be able to try this if they suspect DGD but want to try and save their pets.
Again, thank you all for all that you do and please know that I (as I am sure others) are extremely grateful for every second you devote to helping.
<Very nice to hear this story. It's worth repeating the point that while Dwarf Gourami Disease is a common reason Dwarf Gouramis get sick, not all sick Dwarf Gouramis have Dwarf Gourami Disease. Sometimes they get other things!>
Very Respectfully,
Grace
<Good luck, Neale.>

Re: question re: TB, and Fin damage 4/4/08
Hi again,
You say that TB is unlikely in FW fish but after reading numerous pages on this site I've gathered the complete opposite.
<I don't agree with them. Fish TB has historically been cited by aquarists for all sorts of "mystery deaths", and recent work by scientists has certainly proven that some Mycobacterium strains are common in aquaria. But in my experience, almost all "mystery deaths" are better explained by other factors: Hexamita, poor water quality, genetics, use of feeder fish, and so on. In any event, because Mycobacterium is untreatable, you may as well try to concentrate on things you can fix, in the hope that the fish will recover. If it doesn't, no harm is done.>
Most other people state that if its an adult fish with a bent spine (and its even a Danio ((Glofish but they are the same thing))- at any rate tonight he's laying at the bottom of the tank barely breathing- Hopefully my husband gets home soon because I cant bring myself to euthanize him. Does this mean that this QT tank is now infected?
<What the Czech scientists who looked at Mycobacterium discovered was that the bacteria are present in 75% of fish tanks.
http://www.practicalfishkeeping.co.uk/pfk/pages/item.php?news=1055
In other words, you probably have the bacteria that could cause Fish TB anyway, but then so do I and so do most other fishkeepers. So why don't 75% of fishkeepers have fish dying from Fish TB? That's the question! While you should certainly clean the hospital tank as a precaution -- something you do with a hospital tank anyway -- don't bother getting paranoid about the Mycobacterium itself. By the way, the variety of Mycobacterium that can infect humans is the one most common in marine aquaria, Mycobacterium marinum.>
After reading your email I put two other sick fish in my QT tank with him (I found my black Sailfin molly with skin that looks like it is "decaying" he has holes in his Sailfin and body and the rest of his skin looks like its going to fall off) and the Neon (of which got even MORE white on his body after putting him in there.
<Mollies are never that healthy kept in freshwater tanks. The vast majority of Molly deaths come down to high nitrate and the wrong water chemistry, and I'd bet all the money in my pockets that that's the issue here.
http://www.wetwebmedia.com/fwsubwebindex/mollies.htm
Neon Tetras are very prone to a disease called Pleistophora (or Neon Tetra Disease) that is incurable.
http://www.wetwebmedia.com/FWSubWebIndex/fwdistrbshtart.htm
If you're suddenly getting a bunch of fish looking sick, then I'd first turn to my water test kits. Check the water quality. Neons and Mollies for example require completely different water chemistry, and choosing what's right for Mollies will stress/kill your Neons. So you have work to do there. I'd review nitrate especially, as that's a killer for Mollies. Neons need soft/acid water, and Mollies hard/basic water with salt added at a dose of about 6 grammes per litre.>
Have I gave these fish the death sentence? If they didn't have it already? If not how would you recommend me helping them?
<If the Neon has Pleistophora, it'd doomed so you may as well destroy it painlessly. Mollies usually recover quickly when kept in brackish or marine aquaria, so that's what's required there. As for the Danio, it doesn't look that good to me.>
With my Balas in my 100 gallon how do you recommend I treat that? Like I said they do have some spits/ and frays on some of their fins but otherwise act VERY healthy and seemingly fine.
<Depending on where you are, you'd use different medications. In the UK, I've found eSHa 2000 very safe and effective. Americans like to use Maracyn instead.>
I am hesitant to treat in this tank because its my main and so large yet I cant put them in the small 10 gallon with all the other terminally ill fish-
<Treating the fish in the 100 gallon tank is fine. Used correctly, no modern fish medication should cause undue stress on the fish.>
Ugh...Couldn't I just put in some salt and keep and eye on the fins?
<No. Salt doesn't really have any useful impact on Finrot. Salt can help with Fungus, but only up to a point. Anyway, the salt would stress these freshwater fish rather more than medication.>
And if they start to get any worse treat the whole tank with Maracyn like you said?
<No.>
What a mess I have here. I really shouldn't have "saved" this hunchback Glofish from my dad but at the time I didn't know I had two other "sick" fish.
<No good deed goes unpunished!>
The Molly started with a shimmy and I had him in the qt tank for a few days with salt- put him back in the main tank and 3 days later looks horrible.
<Precisely. I know people sell Mollies as freshwater fish, but they really aren't reliable as such. Sorry, but that's just the way it is.>
and was either laying on the bottom listless or hiding in my deco. in the past 24 hrs. I haven't slept in 2 days because I am trying to change all the water and take care of all of these issues ( I can only do it at night when my baby is sleeping) so if this is a little hard to follow I apologize. Any guidance would be greatly appreciated.
<Gosh, I'm sorry you're having such a bad time! Obviously you have to put children before animals. This being the case, painlessly destroying sick fish would be completely understandable. Lesser of two evils.>
V/R Grace
<Cheers, Neale.>

Re: question re: TB, and Fin damage 4/4/08
Thank you for your prompt reply- I usually keep my mollies in the 100 gallon which is my "semi-aggressive" some salt tank and my Neons in my 20 gallon "community" tank - its my QT tank where they have to be combined. I've been testing my water every few days since my Bala's first started showing the frayed fins (I think it might have been from a new decoration we just put in there)
<Hmm... physical damage can cause symptoms similar fin-nipping. Spiky ornaments can scratch fish that bomb around the tank when alarmed. Though that does raise two points: firstly if your fish are getting scared, that's something that needs to be fixed. Secondly, even if the fins are scratched rather than bitten, Finrot is still a problem. I'd also mention that if physical damage is the issue here rather than nipping, you'd expect to see scratches on the body and/or missing scales, not just frayed fins.>
Am-0, Nitrite-0 and Nitrate 15(aprox)- So do I get all the money in your pocket? (lol).

I am in the US so I guess I need to go out and get a huge box of Maracyn today....should I take my BioWheels out and put them in a bucket of aquarium water so I don't destroy the biological filter?
<None of this is necessary. Maracyn is completely harmless to your filter when used as instructed.>
I was hoping the neon with the white "insides" was a fungal infection from the broken heater issue and not the NTD and I was going to try and treat him and the Molly (and I suppose the Glofish too because today he is swimming around again!
<All sounds very perplexing. NTD typically has the Neon losing colour, becoming shy, hiding away from the group, not eating, and then wasting away. It's highly contagious to other Neons and perhaps other tetras, though rarely affects other types of fish.>
He was acting SO "dead" last night) for fungal/bacteria issues.
<Well maybe there's hope!>
The molly's skin looks REALLY bad.
Mollies can sometimes be improved by giving them dips in "seawater" -- a litre of aquarium water with 35 grammes of salt, ideally aquarium salt but rock or kosher salt will do. Dip the fish for 2-20 minutes depending on how it reacts. That should clean up the skin quite a bit. Repeat daily.>
I do have 4 other molly's in the 100 gallon and they seem perfectly fine as I am in South Texas and the water here is naturally "hard" (high lime content) actually my Ph naturally runs 8.2 -.4 out of the tap- I was told to not bother treating it as long as its constant they will be fine? is this the case?
<"Liquid rock" water is certainly what Mollies prefer. Quite why Mollies are so unpredictable in health when kept in freshwater is unclear. They are common enough in freshwater in the wild. While 100% of the Mollies sold thrive in brackish water aquaria, in my experience, only some Mollies will do well in freshwater aquaria.>
And I have never tested for hardness or softness (not even sure what a test for these would be) because in the things I have read they never stated it necessary- should I?
<If you have rock hard water, then chances are you have hard, basic water conditions. Ideal for livebearers, Goldfish and many cichlids, but not necessarily ideal for fish from soft water environments, including Neons. To be fair though, your water is probably similar to mine here in Southern England -- out of a chalk aquifer -- and most fish adapt just fine.>
Thank you again. I pray my issues get resolved soon.
<So do I! If you have a digital camera to hand, some photos of the Molly and the Neon might help us diagnose things further. Good luck, Neale.>

Zebra Danio acting strangely 5/6/08
Hello,
<Sarah>
I have an established hexagon tank, I believe it is 35 gallons. I had e-mailed last Sept when some of my fish died suddenly after a heater malfunction.
Since that time, I have not added any other fish, we had 1 zebra Danio and 2 Cory cat. This weekend I picked up 5 very small zebra Danios at Petsmart (where the other fish came from as well) and 2 more Cory cats. I have checked the water daily, it still shows zero nitrites.
All the new fish seem to be active and happy. The coloration on the new Danios brightened from a pale brown to bright stripes almost immediately. All the Cory cats are happy. However, the one original Danio is acting strangely. It seems to be swimming in a labored fashion, moving his tail constantly, as if it cannot keep itself straight in the water. Its tail is lower, and its head is high. He has had a bloated look for a very long time, so not sure if it could have some sort of problem. Any suggestions? I had wanted to get more Danios so he would have someone to school with, as he was just hiding in the plastic plants all the time. Now he's out and swimming, but not looking good.
Also, he has a large bright red spot on one side behind the eye- is this normal coloration for zebra Danios?
Thanks,
Sarah
<Mmm, is not... could be most anything at this juncture, description. Please do send along a well-resolved image if you can. Bob Fenner>

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