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FAQs on the Characinine (Tetra) Fishes 

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Re: Your opinion? Now onto Exodon...    2/9/10
Thanks man. The tank is coming along great with your help.
<Glad to help.>
PS: watching Congos eat a full grown insect is a surprisingly educational experience. They are a hunting pack like any other eh.
<Oh yes, indeed! Piranhas are simply scaled up tetras. Do look out for Exodon paradoxus. Very beautiful fish, and if kept in large groups, quite peaceful towards one another. But throw in a piece of tilapia fillet and they go bananas, a true feeding frenzy. Because they're so small, and both pretty and active, they are far better pets than Piranhas, in my opinion, which tend to be rather boring. They also do well on flake, so aren't difficult to maintain.
Cheers, Neale.>
Re: Your opinion? More re Exodon    2/9/10
Interesting you should mention them. I have been planning a second large tank, probably 90gal and was thinking about the famous bucktooth tetra.
<Very good! If you can get them, and keep enough for them, they're good fun.>
My goal would be to replicate their natural environment as closely as practical.
<Similar to that of other tetras, really. Swimming space, plenty of shade and overhead vegetation (they're notorious jumpers). Likes a good current, but not turbulent.>
What tank set up would you recommend?
<Despite their small size (10-12 cm long is about how big they get in a home aquarium) I'd recommend a fairly large tank, so you can keep a good number. There's debate about the minimum needed to avoid cannibalism and
bullying, some say 10, some say 12, but if you plan for around 20, you won't go wrong. I'd be looking at something around the 150-180 litre, 30-40 gallon mark.>
Any tankmates?
<Heavens no! Their buck teeth do seem to be about pulling scales and fins from other fish.>
I'm up very early each morning and so enjoy the night shift as well as pretty day fish.
<Well, these are probably crepuscular, much like other predatory characins, so won't be at all bothered by early mornings, late nights. In fact giving them two good feeds per day, with 10-12 hours between for the filter to mop
up the mess, is probably ideal. Hungry fish are more likely to be cannibalistic than well fed specimens. This sort of "overfeeding" is precisely how public aquaria keep sharks in tanks seemingly filled with bite-size prey.>
On that note, what type of lighting would you recommend for night time viewing?
<I'd have thought a simple Grolux tube would be ideal, bringing out their reds.>
Forgive my spelling and grammar I'm doing this on the phone crammed into the subway.
<Cheers, Neale.>

Re: Cichlids...  toothy Characiforms, Polypterus... rambling 2/2/2010
Well all the eggs died when I got home. The festae is cleaning them off as I type this. The payara is actually a Raphiodon vulpinus.
<Actually, Rhaphiodon vulpinus is the Biara rather than the Payara, though they're both in the same family. This is the problem with common names. In any case, another species that doesn't live long in home aquaria. You'll
read plenty of reports of people with juveniles a few inches long doing just fine. But without fail, once they get to a certain size, under 30 cm, they stop eating and simply die. Possibly it's to do with lack of water current or oxygenation, or perhaps a social behaviour thing, but whatever the issue, these fish simply don't do well in captivity. Few last more than six months.>
Even so, he will stay alone. The payara is in a totally separate tank and is fed live foods only. He is extremely stubborn with frozen foods.
<As with any predatory fish, the more patient and stubborn you are, the better the outcome. Earthworms and river shrimps are good live foods that remove the need for minnows or goldfish, neither of which should be used as
feeders under any circumstances. Home-bred cichlids, killifish and livebearers are acceptable if gut-loaded, but expensive, and that's even before we discuss ethics.>
I've used beef heart, bloodworms, krill and silversides. He gave he slightest reaction to silversides, but wouldn't eat them.
<The art to silversides and lancefish is to throw them into the water current, so that they look alive. It's also possible, and indeed advisable, to train fish to be fed by hand. I use forceps for this, and you would certainly want to do likewise with a 60 cm characin with fangs! Anyway, to see an example of this, visit the TFH web site, where there's a video of me feeding my Pike Characins (see the Feb. 2010 entry):
Hand-feeding lets you give precise amounts of particular foods to your predators, so you can ensure proper nutrition.>
Would you think those two cichlids you talked about could go in with the Polypterus in that 20 gallon?
<No. Both are hard water fish, Rhamphochromis from Malawi, and Altolamprologus from Tanganyika. There are actually some very nice small Altolamprologus species, even shell-dwelling species, but these fish do require specific conditions.>
Or the Firemouths?
<Possibly compatible with Polypterus, but not in a 20 gallon tank. Look, no Polypterus species is small enough to be happy in a 20 gallon tank for life. Even the smallest species are about 35 cm/14 inches long when mature,
and while it takes a few years for them to get that size, grow they will.
So why not plan on keeping fish of appropriate sizes and types in he tanks you have, and rather than trying to cram lots and lots of fish into a tiny space. I sense youth in your questions -- trust me, when we started out, we all went through the "stamp collecting" phase of wanting everything. But believe me when I tell you that you'll never be able to keep all the fish you see or want. Much better to choose one or two species or habitats that interest you, and build up your tanks so they hold that interest in the long term. For example, why not choose a cichlid species that isn't easy to breed, so that you can observe rarely seen behaviour, and then sell on valuable fry? Or perhaps think about creating one particular habitat, like an African swamp or a Central American river, and choose fish slowly
towards that goal.>
So the pikes are out of the picture now, and I'm considering other options.
I like the Firemouth idea and but what about a different cichlid, one that can be kept with the Dempsey and festae?
<Not much can be kept Cichlasoma festae, to be honest. Does depend on the size of the tank of course, but adding new fish to a tank with an adult, sexually mature C. festae is asking for trouble.>
Thank you.
<Cheers, Neale.>
Re: Cichlids
Thank you for the tip on specific tanks.
<You're welcome.>
I am only 12 so sensing youth is correct. The Polypterus is only 6 inches right now and I was planning on moving him in with the breeding pair when he's bigger.
<On the whole cichlids and bichirs don't cohabit well. I'd keep them apart.
The problem is that bichirs move very slowly, and because they live on the bottom of the tank, they often stumble into the territories of breeding cichlids. Lacking speed, they can't escape easily, and they end up being bitten. Furthermore, I've seen relatively peaceful cichlids strip the fins from bichirs. In short, I'd recommend against it.>
I'm guessing I should keep him alone in the 20 and progressively add fish with him as he moves. I would really like to keep something with him now though, with him being nocturnal and all it gets pretty boring.
<I'm assuming you have the standard bichir species of the trade, Polypterus senegalus. This is a fairly peaceful species and actually works best with some dither fish. Dither fish are schooling, surface water fish that "tell" fish living at the bottom that there are no predators about. In the wild bottom dwelling fish look for open water fish; if they can't see them, they stay hidden. Good dither fish for Polypterus senegalus would include any schooling fish that stays out in the open. Congo Tetras are the classic choice since they're African fish as well, but anything too big to be viewed as prey will do: Swordtails, Rainbowfish, medium-sized tetras, etc.
Obviously the tank needs to be big enough for the schooling fish to feel settled, so a 20 gallon tank would be too small. I'd consider 30 gallons the minimum for an adult Polypterus senegalus.>
I don't know what I could do. With the breeding pair in their 58 moving into a 75, what else could I keep with them? Thank you.
<Take a look here:
There are some photos of a nice African community plus various fish.
Cheers, Neale.>

I am obsessed with keeping freshwater cardinals! I just can't keep them alive!   5/13/07 Hi! <Hello!> Hope all is well with you.  I have a question I hope you can help me with. I have had reef and saltwater tanks for a couple of decades, and I do pretty well. I even have a 600 gallon one in my kitchen wall! <Sounds nice. Though if you prepare sushi in the kitchen, I imagine the fish get rather nervous wondering if they're next...> But I am obsessed with keeping freshwater cardinals! I just can't keep them alive! <I we talking those neon tetra look-alikes, Cheirodon axelrodi, or the freshwater examples of the marine cardinals such as Glossamia aprion, the "mouth almighty"? I assume the tetras.> I have a 45 gallon tank with a sump. (an old reef tank). I had it setup with a BioWheel, and gravel on the bottom. I suctioned the gravel monthly, did a 33% water change monthly, and no luck with the cardinals. <Cardinal tetras can be tricky for a variety of reasons, but once settled in they're basically tough little fish. The main problem in my experience is Neon Tetra Disease (NTD), which works its way through cardinal tetras at about 50% mortality, i.e., if you buy 20 cardinals, and you get the dreaded NTD, you can lose up to half of them. Better than neons, where you lose all of them, but still annoying. Another issue with cardinals is they are all wild-caught. In fact, they're the most numerous exported tropical fish from South America. Anyway, by the time they reach the market countries around the world, they might not have eaten for weeks. My guess is that healthy, well-fed cardinals are more or less NTD resistant, but when weakened and cooped up in a retailer's aquarium, they are far more susceptible to this disease. So as with any wild-caught fish, buying when a new batch arrives can make sense, and then quarantining and feeding on a variety of live/frozen foods makes all the difference.> I then added an undergravel filter (I know....dumb idea, but I was desperate!) <There's nothing intrinsically wrong with UG filters. They do a good job of maintaining water quality. The problem with UG filters is their incompatibility with aquascaping and rooted species of plants more than anything else.> No luck. Nitrates off the chart. Dead cardinals. <Odd, given how small cardinals are. They don't eat much (and don't need to eat much, either). They're classic "pinch of flake a day" fish in my book. When you say "off the scale" you mean above 100 mg/l? What is the nitrate level of the water out the tap/faucet? I have to confess to keeping mine in rainwater with a bit of tapwater added. Seems to work well.> Someone suggested bioballs.  Would not that make the nitrates even higher? <Worth trying I suppose but I don't find nitrate removal systems in freshwater tanks to be of much value. Freshwater fish don't care that much provided the rise in nitrates is slow, and even between 50-100 mg/l you shouldn't get mass die-offs of fish except with certain species (Tanganyikans for example). Simple water changes are, IMO, a better approach to nitrate management, and the filter is best devoted to biological filtration, i.e., ammonia/nitrite management rather than nitrate.> I have used Amazon rain additive (is that stuff any good?) <Not really. Looks nice, but doesn't really do anything if you have hard, alkaline water. In softer water, may help acidify the water a little, but approach the concept of acidifying water with caution, as it's easy to mess up.> No luck. PLEASE do you have an ideas?  Thanks! <Have a read of this: http://www.wetwebmedia.com/ca/volume_2/cav2i3/cardinal_tetras/Cardinal_Tetras.htm for some more ideas.> Ron <Cheers, Neale>

Rummynose tetras and cardinal tetras hi, I'm considering buying some Rummynose tetras and cardinal tetras for my tank (which will be well planted before I get them, although its a bit sparse now).  ( also I think the species of Rummynose available near me is H. bleheri but it could be H. rhodostomus, I don't know how much difference that makes in the behavior and health of the fish?) In the store these two species seemed to be schooling together well. I'm wondering therefore, if its necessary to get a "full" school of each (at least 6 fish), or if I can do with a partial school (3-4 fish) of one of these two and a "full" school of the other?   Since I am a little short on tank space and want to avoid overcrowding.   Also if I do get a partial school, which species should I do that with? lastly is there any other general advice you can give on either of these species? :) < Both species like warm acidic water. Your Rummynose is being bred in Asia too. It makes no difference which species of Rummynose you get. The Asiatic varieties are a little more tolerant of poorer water quality. You can always start out with three of each species and if they don't fully color up after a week or so you could always add more. The Rummynose will be the hardier of the two fish so I would start a new tank with those first and add the cardinals later after the plants get going.-Chuck> thanks, ~Anna

Re: Rummynose tetras and cardinal tetras Ok, well the tank is already going, earlier this year I was able to set it up with some rasboras, a couple other fish, and a few plants, then my income (selling on eBay) dried up so until recently I haven't been able to do anything more with it.  Right now I've got ordered everything else the setup needs except the rest of the plants and the fish :)   Thanks for the advice, I will try that with the tetras (waiting a week to see if they color up) My water is usually just under 78 degrees (or just over 75 - hard to tell exactly with the little color strips but it is pretty stable where it is, anyway) and my pH pretty consistently 6.5 (that's the pH of our tapwater, which I of course condition due to chlorine)  Do those conditions seem ok? < Soft warm water seems just fine.> the rasboras (6 harlequin and 3 scissortails, we had 5 at one point but 2 died and the rest seemed to stay colored up fine so we didn't replace them), Cory and Oto (yes I plan to get more of both of those) all seem to be quite happy with the tank.  if I need to I can raise the temperature over time, if a higher temp would be better? < You might kick it up to 80 degrees F to prevent any outbreaks of ich and you fish will be a little livelier.-Chuck> Anyway, thanks for your help, you guys are very useful! ;) ~Anna

Tetra Question Chuck:  New thing here.....my diamond tetras keep raising their dorsal fins. No serious aggression seems to be involved with this, but can you shed a little light on why this might be happening, and tell me if it's something I need to do anything about. < Your diamond tetras are displaying to one another. Either males showing their dominance to other males or displaying to females. Nothing to worry about just cool to watch.-Chuck> Thanks, Cyndy M.

RE: Tetra Question In regard to rinsing the pads with a high pressure hose, is having that amount of chlorinated water on them okay when I place them back in the tank? < No problem. Just shake them off real good so they are barely dripping.> There's no way to dechlorinate the water coming from my hose, obviously. Also, when I "cleaned" the bio-filters, I simply swished them around in a bucket with a little dechlorinated water in it.  Is this sufficient and how often should I do this? < I would shake them around in a bucket of water I have siphoned from the tank to make sure that the bacteria on the wheel don't get knocked off by some chlorinated water.>   As for overfeeding the fish, I never SEE any settle to the bottom when they eat, and they always seem to be hungry, so how do you know if you're overfeeding if you can't see any food on the bottom, or does that tell you that you're not? < Once again, give them only enough food so it all is entirely eaten in a couple of minutes. If it is all gone in ten seconds then obviously you could feed them more. Some should make it to the bottom for fish that stay there all the time.> (Forgive the run-on sentence) Just a note of good news, since all I seem to write you about is the bad....since I set the temperature at a constant 77 degrees, it seems to have had a magical effect.  The fish just seem more comfortable and their colors are appearing brighter and deeper. They seem happier in general, particularly the angels.  I'll keep my fingers crossed that this temperature thing plus twice a week water changes and detritus cleanings continue to be the ticket to a healthy tank. Lastly, in the 10 gallon hospital tank that I am presently cycling using old filters and water from the cycled tank to help things along), I have a school of red-eye tetras.  In with them, I have a quartz rock, black substrate, and four plastic plants.  I purchased them on Monday, and they are still moving in the background and not venturing forward to the front of the tank.  They don't appear to be uncomfortable with the nitrites (now at .25, but presumably this might get worse as the tank cycles), and I used Aqua Safe to neutralize what little ammonia there was (.15) (after taking the readings, as I know chemicals can mess up a reading).  Is this normally a shy fish? < They can take awhile to become accustomed to their new surroundings.>   Also, the big tank is cater-cornered to their tank...could they be afraid of fish in the big tank or the light coming from that tank? < Probably not.>   In other words, they don't seem chemically stressed, but emotionally distressed.  Hope you don't think I'm the village idiot for referring to my fishes feelings, but I do feel a certain empathetic bond with them-strange as it seems. < Tetras seem to take some time to settle in. Sometimes that don't look to good in a store but really shine when you get them home.-Chuck> Sorry for rattling on.  Thanks for all you've done and continue to do...you're my fish knight in shining armor! Cyndy

Re: Tetra Question Chuck: To refresh your memory, I'm currently using 6 Red-Eye Tetras to cycle a tank. So far, it's on schedule, and I've done water changes every couple of days to help it along-plus I used media from my established tank.  Although all the tetras are swimming along and seem okay, I noticed today that one of them has a red blood-colored spot right alongside and possibly behind his gill cover.  Any idea what this might be?
< Could be a bacteria infection if it is a bloody looking spot. If it gets bigger then you will need to medicate with furanace. This medication may harm the bacteria you are trying to establish in you tank so cycling may take longer.-Chuck> Cyndy Monarez

Keeping two different types of tetras together? I really like your site! I haven't found anything else like this for the serious aquarist! I can spend hours here! Now to my questions. I recently bought 6 lemon tetras (Hyphessobrycon pulchripinnis) and 6 Buenos Aires tetras Hyphessobrycon anisitsi). I'm keeping them in the same tank. I thought that maybe they would school separately but they all seem to be schooling together, which is good! I read the Buenos Aires tetras can be nippy. Is it OK to keep these two species together (if species is the correct term)? < Watch those Buenos Aires tetras, they will definitely nip at the others when they get hungry. They get bigger than the lemons too. Your terminology is correct.> Should I follow the "odd rule" with schooling fish like this? < Sorry , don't know what the "odd rule" is.> Also, at some point, I might want to try spawning them. I'd move them into separate tanks, of course, but can they cross breed? < Not really.-Chuck> Just curious. Thanks! Steven Beatty

Question: Glass Headstander - Charax gibbosus I purchased a "Glass Headstander" Charax gibbosus around 2 inches 4 days ago.  I did some research about its diet/requirements but nothing much turn up, so I turn to you guys !!  It hasn't eaten anything yet.  I'm keeping it in a 10g with 5 baby convicts(1cm).  It has quite a big set of teeth and large mouth like an Exodon.   The store I bought it from say it's quite aggressive but I have yet to see it attack anything. I tried krills, flakes, beefhearts, floating foot sticks but none worked so far. Thanks, Kevin <<Dear Kevin; my search can up pretty empty, also. I found an adult size (12 cm) and pH requirements, 6.0 to 7.5. Aside from that, not much out there. If you are having trouble feeding him, I recommend trying frozen bloodworms or brine shrimp. Give him a few days to settle into new surroundings, too. Was he eating in the pet store? You can try calling them to ask what they were feeding him. I'm not sure if these fish should be kept in groups or not...also, make sure your water quality is up to par, that is, no ammonia, nitrites, and low nitrate readings. Please test your water! -Gwen>>

Tetras My family and I have a 20gallon tank with 2 guppies, a catfish, a pleco, 5 neon tetras, and 3 Von Rio tetras which we got at a local store.  The 3 Von Rio's appear healthy except for one which has a "kinked" or crooked spine.   <crooked spines typically are signs that either the fish didn't get the proper minerals/nutrients during it's development, of that it's a genetic birth defect.  Both of these scenarios are not fixable.> I also noticed that the shape of his head is different than that of the others.  The thing that bothers me about this fish is that whenever he is gliding or attempting to stay in one spot his tail starts to sink to the bottom. <A head deformity is often times seen with spinal problems.  With most fish breeders, offspring with poorly shaped bodies are typically culled.  The sinking of the body is most likely thanks to the oddly balanced body shape... it's harder for him to remain neutrally buoyant.> All of the other fish appear healthy and are doing great, they are active and eat well and we change about 15% of the water 2x per week we use a gravel vac while doing this.  I am hoping that it is just a genetic defect and not a disease, I've researched online and haven't found anything that looks like what this Tetra has, could you clue me in? <You are correct, it's not a disease, and your other fish aren't in any danger.  Keep the water fresh, and make sure that it gets food, and it should lead a relatively normal life.  Good luck. -Magnus>

Neon tetra with one eye (1/23/04) Hi, I have just recently added 2 new Neons to my tank and I just recently noticed one of them is missing an eye. Could you tell me if this happens often and do I need to do anything for the little fish? <It doesn't happen often, but does happen. Keep your water quality high -- ammonia and nitrites at zero, nitrates 20 or less. And watch the fish when it's feeding time to make sure it does get something to eat. If it doesn't, you might want to put it in an isolation tank.> Thank you so much.  Carlie <You're welcome. --Ananda>

Neon Tetra disease Hi Steven or Anthony, <Anthony Calfo in your service> Have either of you heard of any updates regarding the treatment of Neon Tetra Disease (Pleistophora hyphessobryconis)?  <alas...nothing beyond the standby of Naladixic acid> Despite reasonable precautions (QT, broad-spectrum prophylaxis), it is devastating my species tank. While my Corydoras seem immune to this parasite, do you know if they are carriers?  <much debate on the topic even if you had the skills or desire to pull out a microscope. Best bets include running QT with the tankmates (like the corys) for more than 4 weeks with the hope of reducing or breaking the cycle> Thank you for all of your help. Bryan <I wish that I could do more my friend. Anthony>

Dying Neons Hello Anthony,  <Howdy, friend!> I have a four week old twenty gallon freshwater Aquarium. my pH is at 7.1 and my Ammonia is at 0 PPM. I have four small Cory catfish, and used to have sixteen neon tetras, now only eight. in the last five days I have had eight neon's die on me for at first no reason, until about yesterday I found a small white dot on the head of most of the dead neon's that looked like a type of fungus. the first time I put in the neon's I found one with a white patch on its back right next to its dorsal fin, I brought it down to the pet store where I had bought it and they said it looked like neon tetra disease.  <yes...common and devastating> So I treated it with half the recommended dose for two days and saw no sign of neon disease. Right now I have no idea what it could be. The really weird thing is that they show no trace of the dot the day before they die. I am really hoping you can figure this out. Thanks. Peter <tough call... do they behave fine in general just before they die? And were you using a medication with Naladixic acid. If so, you may look towards another disease or mild toxin. Try a poly-filter and extra water changes to see if that helps. Best regards, Anthony>

Information please (Looking to buy fancy tetras) Please email with information as to where I can purchase some of these fish called Chalceus macrolepidotus...with yellow tails. I have been trying to locate them for some time now , I have 2 with the red tails I would appreciate any information you might have send to The XXXX also if you would send the phone number of any stores that might carry them . Truly Yours, Donna <Mmm, my sisters name... I would check with fish stores located near you, re their ability to "special order" this species... Most stores will, all can make these requests with their suppliers. Bigger stores that may be within driving distance can likely be found in your areas "Yellow Pages" telephone directory (You don't mention what part of the world you're in, but do check with the local library if you don't have outlying phone book directories) Otherwise there are freshwater livestock "etailers", some listed on our Links Pages: http://www.wetwebmedia.com/links.htm That you might contact with your request. This species ships fairly well. Bob Fenner>

cardinal tetras Dear Robert, how long does it take for the cardinal tetra to acclimatise to my tank - the red color is still a little faded. I added them to my tank today. <Hmm, most often a few days... sometimes "never" though... due to less-than favorable conditions... Cardinal Tetras prefer soft, slightly acidic waters of elevated temperature. Best kept in "live plant" settings with stocks that prefer those conditions. Their "redness" is a good bio-indication of the suitability of their environment. Bob Fenner> Keith :)

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