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FAQs on Otocinclus Compatibility

Related Articles: OtocinclusLoricariids

Related Catfish FAQs: Otocinclus 1, Otocinclus 2, & FAQs on: Otocinclus Identification, Otocinclus Behavior, Otocinclus Selection, Otocinclus Systems, Otocinclus Feeding, Otocinclus Health, Otocinclus Reproduction, & Suckermouth Catfishes of South and Central America, Loricariid Identification, Loricariid Behavior, Loricariid Compatibility, Loricariid Selection, Loricariid Systems, Loricariid Feeding, Loricariid Reproduction, Loricariid Disease, Catfish: Identification, Behavior, Compatibility, Selection, Systems, Feeding, Disease, Reproduction Algae Eaters

Social species... should be kept in a shoal/group... Tropical... not cool/cold water... Freshwater (Amazon), don't like salt/s.... or aggressive, fast moving tank mates.

Albino Cory Catfish. Oto incomp.    11/5/11
Hi there,
I have a 30 gallon freshwater aquarium that has been well established for over a year. All of my fish have been together since the beginning. I just recently did a 75% water change and added new plants (water changed due to long interval of no water change and new plants were boiled for 15 minutes and rinsed with old aquarium water prior to placement in the tank) I have tested my water with colored test strips, everything appears to be perfect. I currently have in the tank the following: 3 albino Cory, 2 zebra danio's, 14 neon's, 1 frog, 1 snail, and a monster of an algae eater (Otocinclus) that has become a bit aggressive and very large. The problem is with my Albino Cory his top or upper fin looks as though it has been nipped, he is well for lack of a better word tipping.
<Mmm, the Oto...>
He can not seem to keep balanced in a stationary position like he use to. Also, resilient as he is, he has started 'lodging' himself against plants to stop from tipping. I can not say with 100% certainty that he has been eating but he has been coming up for air like normal. Also, I have noticed his breathing is much more labored than usual and much more than my other two. What can I do I have had the Cory fish the longest and do not want to lose him. Thanks for you help.
<I would move the Otocinclus elsewhere. Cheers, Bob Fenner>
Destiny Nash

Otocinclus with eyes missing    6/1/11
I just purchased four small Otocinclus catfish. While the salesperson was catching them, she noticed that one was missing an eye and removed him, commenting that "someone must have been picking on him". I thought the others looked healthy but obviously I didn't look closely enough. When I got them home, I noticed that two have an eye missing, and one has no eyes at all. There is just a pale spot where the eyes ought to be. The fish behave normally and don't seem to have any trouble locating food. Do you think this is an injury-- some vicious eye-eating tankmate? Or a disease?
What do you recommend we do? Thanks for your help!
<Hello Jan. The good news is that the loss of an eye seems to cause most fish no problems at all. Eyesight is a far less important sense to fish than it is to humans, even though most fish have excellent eyesight. So a one-eyed fish can be bought and enjoyed with confidence. Otocinclus, being catfish, have excellent senses including smell and touch thanks to their barbels, and I'd expect even a no-eyed individual might do okay, though it would probably benefit from being kept alone for a while and getting offered its own food, such as algae wafers. If it looked skinny -- something Otocinclus are prone to anyway -- and failed to put on weight even with good care, then euthanasia might be appropriate. As for why the fish has lost an eye, that's usually fighting between fish in the tank.
Dwarf cichlids for example will attack small catfish and bite out their eyes, something many casual aquarists don't realise. Failed predation attempts, pop-eye, and rough handling by the fishkeeper can also cause damage to the eyes, and once damaged, infected eyes often fail to recover and simply fall off. There's no treatment as such, and provided the fish can feed normally, one-eyed fish usually live long and happy lives. Cheers, Neale.>

Otocinclus.. sys., comp., beh.    3/22/11
My name is Jessica, thank you for your help in advance. I have been keeping Goldfish ever since I got my first ten gallon aquarium at the age of nine.
For the past two years, I have had a 29 gallon freshwater planted tank, which is also home to one brand new, week old, two inch Fantail Goldfish and two Otocinclus.
<Mmm... not really compatible fishes... like very different water quality mixes>
The tank parameters are as follows, pH 6.4,
<Low for Goldfish>
Nitrites 0, Nitrates 20ppm or less,
<I would not let the NO3 concentration get any higher than this maximum>
Ammonia 0, and temp 70-72F. I do a weekly 25-50% water change and vacuum the gravel at the same time while tending the plants. It is well water so I don't need to add a dechlorinator. I bought the two Otocinclus about two months ago and they have done an amazing job cleaning up the algae in the tank. At the time the aquarium was home to an eight inch, five year old Bubble Eye Goldfish who has since passed on. His one eye bubble got so big that he kept catching it in his mouth. It became irritated and in the 24 hours that I was not there it managed to become infected and swollen. I placed him in the hospital tank and gave him antibiotics but sadly his eye popped and he died two days later. Since then I have been substituting the Otocinclus's algae diet with some zucchini and spirulina wafers and have left the back and sides of the tank alone for them to clean. When I first got them they both had Ich and one of them had almost its entire caudal fin missing. Unfortunately, I read that this was rather commonplace during the shipping process.
<This is so>
Anyway, its fin has regrown and they both seem to be doing fine. What concerns me is that their dorsal fins always seems to be held tight against their bodies, they have been this way since I got them, is this just normal behavior for them?
<Mmm, yes. A general statement re freshwater fishes is that their fins are "down" for most of the time, vs. marine fishes, whose fins are "up" most of the time>
They seem happy otherwise zooming around the tank and they really love their zucchini, although the new goldfish is fighting them for it. Also, I was thinking of raising the pH just a little bit, up to 6.8, and to this end was thinking of boiling some shells, cracking them, and placing them in a glass bottle in the tank.
<Worth trying>
That way the fish could not get cut on them and they would be easy to take out if the pH got too high. Do you think this is a good idea or would you recommend to just leave the pH alone as is?
<I might instead add a bit of sodium bicarbonate (baking soda) to a given batch of make-up water (in storage and tested ahead of use) to get a proportion of how much you'd be adding to raise the pH on a regular basis... but the shells are again a good/safe source. Bob Fenner>

Oto question, sys., comp., repro.   9/6/2010
Here's a little background.
My wife and I recently setup a new 10 gallon tank.
<A small tank; not recommended for community tanks.
We got an internal filter. We use a heater (which raises the temp by 4 degrees), the temp is usually 73*F without the heater, but based on the fish we had, I thought 77*F would be a better temperature,
<Does depend on the fish.>
and our heater doesn't have a setting (other than on or off). For now we leave it plugged in and achieve 77*F. We started with 2 Neon Tetras, 3 Black Mollies, and 1 Otocinclus.
<72-75 is ideal for Neons and Otocinclus, but tank-bred, fancy Mollies really need slightly warmer conditions, 77-82 F.>
One of the Neons died within 24 hours. The other neon became so lonely, it stopped playing in the bubbles, it stopped eating, and died of loneliness within a week (even the mollies wouldn't play with it when it tried).
<Let's step away from ideas of "playing" and "loneliness". Neon Tetras are difficult to keep unless you have cool, soft water. You're aiming for pH 6-7.5, 3-10 degrees dH. They won't do well in the hard water Mollies MUST have to stay alive. So these two species are NOT compatible. Neons also need to be kept in groups of 6 or more.>
We added 2 more Black Mollies, all these fish so far have come from PetSmart.
<Mollies really won't do well in 10 gallons of water. The males are aggressive towards each other and the females. They are also very sensitive to poor water quality, making them bad choices for new tanks. Do read here:
After a few more visits to PetSmart, we noticed that some of their fish had Ick. We then noticed ours did too. We tried 2 treatments (1 and then another 24 hours later as per the directions) of a bubbling type tablet that was supposed to clear the Ick.
<Hmm'¦ with Mollies, your best bet is the salt/heat method.>
It removed smaller spots of the Ick, but the Mollies still had large amounts on them. Unfortunately we couldn't afford the treatment when we first noticed it.
<Salt is cheap, so not treating fish for Ick shouldn't ever be an issue. While aquarium salt is ideal, any non-iodized salt should work fine as well.>
I think we noticed it on a Tuesday, and we bought the treatment on Saturday and started administering it Saturday evening. One of the female Black Mollies died the Friday before we got the treatment on Saturday. So, by Saturday, we had 2 males and 2 females (Black Mollies). We still had our 1 Oto (I believe female based on the fact it immediately started going up and down the tank and across the tank almost immediately after we got the heater to raise the temp to 77*F.
<You can't sex Otocinclus this way.>
Websites also suggest this is the perfect temp for breeding Otos. (I had no idea).
<Actually, Otocinclus should be kept fairly cool. They are extremely sensitive to low oxygen concentrations, and as you hopefully remember from school, the warmer water gets, the less oxygen it holds.>
As a side note, we also have lots of snails, and they have been fruitful and multiplied. We started with 1 Black Mystery Snail (fully grown) and about 12 baby snails (golden and black mystery mostly). Long story, but we were wanting 2 or 3 babies, but we ended up with about a dozen of them. Most of the baby snails died off (presumably suffocated).
<Actually, Apple/Mystery snails do bad in aquaria. Don't keep them with fish.>
Before we knew it, there were little specs above the water line. Our 2 airstones were moving water rather violently at the surface, and the filter sucks in water, then pours it onto the surface. This was perfect for the snails as they could put their eggs above the waterline and they would constantly be wet by the popping bubbles. I suspect the Otos also enjoyed the constant streams of current as well. By the way, I am sinking every snail egg I find right now. Well, most aquarists would have suggested that a new tank is the least likely scenario for fish to breed. Not only did the snails breed, but the Black Mollies bred.
<As is their wont.>
One day I found a little fry at the bottom. I about had a heart attack since I never even knew the Mollies were thinking of reproducing.
<I think "thinking" is over-egging the pudding a bit. Males will inseminate anything vaguely Molly-like, and do so persistently. In a 10 gallon tank, the females get stressed and often miscarry, which you can recognise because miscarried babies are either stillborn or so weak they fall to the bottom of the tank. Healthy newborn Mollies can swim immediately after they are born, and instinctively hide among floating plants *at the top* of the tank.>
I went to bed and prayed that it would survive.
<Prayer has it's place, I'm sure, but there are some more immediate things you can do to keep Molly fry alive. Do read the above article.>
By the next morning I wanted to save our little Molly and make it some makeshift tank to keep it from being eaten. (Where there's a redneck, there's a way). Keep in mind, that we are very financially struck at this point.
<That's fine. Here's a tip: stick in some floating plants. Floating Indian Fern is ideal, but even "goldfish weed" like Brazilian Pondweed works well. The fry will hide there and won't be eaten. Plus, floating plants give the female cover, and that reduces the stress they get from amorous males.>
So, I found a casing that is used as a top to CD's. (if you go into Wal-mart and state that you want to buy about 50 blank cd's You will get a container that has a very large round lid. Since we still had one of these containers, we simply took the lid off and turned it upside down. It may not be large, but hey, it's what we can afford for the little fry.
<Have done something similar myself. Use a screwdriver to punch a few dozen small holes in the side so water can in and out, and so much the better! If you don't do that, you'll need to change the water in the container at least once a day.>
I went to find it and it was gone. I even moved the shell and gravel around where it had been hiding the night before. We have about 12 large shells throughout the tank.
<Often what happens with very weak fry is they die, snails come into the floating trap overnight, eat the carcass, and then the snails crawl away.>
The gravel is a bit rough and not exactly ideal for fish tanks. I feared it had been eaten. Several days later, we found one that looked similar to it, hiding in the back. I believe it's the same one, my wife disagrees.
<Molly broods can be anything up to 100 fry, though commonly 20-30.>
Either way, we caught it and put it in this makeshift tank I mentioned. My wife got the idea that we should take one of the air stones out and simply place it in the makeshift tank.
This seemed like a good idea at the time. I mentioned that it wont have a filter or heater, but she doesn't have any idea how to solve that. We put a shell in it too. The little fry loves to hide inside the shell, or near the air stone. After trying to look through my daughters binoculars backwards, I did see it fan its underside fin out showing me that it is a female, because the males have a longer pointy fin in that location.
<You can't sex Mollies at this age. The males won't develop their gonopodium until they're about 2 months old. Until then, they look just like females.>
It is still too young to know for sure, but I believe it is a girl. So, now back to the Otos, which is what I am really interested in. Since the one Oto was trying to attract a mate, and there wasn't one, we bought 2 more Otos.
<Not trying to attract a mate, trust me. These are SCHOOLING fish and want companions.>
PetSmart didn't have any and hasn't in the few weeks since we had bought the first one (the only one they had at the time). We had to go all the way to Norman Oklahoma from Bethany Oklahoma just to get Otos that day.
<I assume that's a long way'¦?>
None of the PetSmart stores has any in the greater Oklahoma City area. So we went to "Wet Pets by Steve" in Norman, Oklahoma. We bought 2 Otos (I wanted at least 1 male). When we looked at the Otos, I was unsure how to tell the sexual differences in Otos (I just had some very generic ideas from what I had read online).
<You can't sex them. Mature females become fatter when filled with eggs, but that assumes they're sexually mature and "conditioned". Specimens in pet stores won't have eaten properly for weeks, so the chances of the females being ripe with eggs are next to zero.>
The gist of the online info was that males are smaller and thinner. The females are larger and potentially rounder. I noticed 1 Oto that was certainly different that the one we had. If you could imagine a line between the Otos eyes, and draw a triangle to its tail, that is what our original Oto looked like. But this one was different, the triangle only went down about half way down its body, then narrowed severely. It was almost like it got pinched on the hind end. I figured this meant it was a male, and the ones I am calling triangular are female. The little guy was very active. We bought it, and another one that I believed was female. I figured that if I bought 2 different ones, there would definitely be at least 1 male and female in the tank.
<Actually, you need to get at least six of them for Otocinclus to be happy. Forget about males and females. You can't sex them.>
When we acclimated them to the tank, I noticed that they were a lighter color, they were smaller, and my wife noticed that our original Oto has bigger eyes.
<More than one species in the trade: Otocinclus affinis and Otocinclus vittatus are the commonest.>
The three of them do hang out quite often, but the one I believe is male, is favoring the new female (not the original). None of them are doing the chase and follow routine. I read online that Chinese Algae Eaters are sometimes mistaken for Otos.
<You'd have to be legally blind to confuse Chinese Algae Eaters with Otocinclus! They are completely different. Otocinclus are much smaller, 1.5-2 inches, tops, Otocinclus affinis is grey above with a thick black region along the midline of its body from nose to tail, and off-white below. Otocinclus vittatus is essentially grey above, darker grey along the flanks, with a thin pale band between these two grey regions, and then off-white below. The Chinese Algae Eater (Gyrinocheilus aymonieri) is more or less green all over with a few bluey-green patches along the top surface and a distinctive zig-zag bluey-green stripe along the midline. The Chinese Algae Eater is big, fast-growing fish that gets to about 8 inches within the first year and around 12 inches within the second. It is notoriously aggressive and has no place in a community tank.>
I am hoping that we have 3 Otos. The littlest one (the one I believe is male) is not afraid of the Black Mollies (as the others will get out of the Black Mollies way when picked on). In fact, it even seemed to attack the Black Molly who bothers it. This seemed very strange to me for a tiny fish to stand up to and even fight back against a much larger fish. The Black Mollies have learned to leave it alone.
<Hungry Otocinclus have a bad habit of rasping at the bodies of other fish. They scrape at the body eating the mucous, but in the process they create nasty wounds. Some fish learn to avoid them, which could easily explain why the Molly seems nervous around them.>
The 2 new Otos are about an inch long (or slightly less). I believe our original Oto is full grown, but still short of 2 inches (I have no easy way to estimate its size). So, now on to the good stuff. Long before we added the new Otos, I had performed a 50% water change. In the process, we noticed a clear gel on the back of the filter. Not knowing what it was, we tossed it out. I later, realized it might be Oto eggs. The snails are all mystery snails and lay their eggs above the water line. The Black Mollies are live bearers. The Neon Tetras died before even the idea of multiplying. So by process of elimination, I figured the gel had to be Oto eggs.
<Likely snail eggs.>
A quick reference on the internet confirmed this is a very likely scenario. I eventually noticed 3 new areas of these egg gels. 1 of the gels got scraped while trying to catch the Molly fry. I eventually scraped the rest of it off the side of the tank where it was and let it fall to the bottom. It seems I am finding several of these egg gels now. I am concerned that our tiny male may not even be an adult yet (and that our 2 females may have to continue to be "ladies in waiting"). I noticed one of the group gels just disappear.
<They're snail eggs, likely from Physa or Physella spp. snails. Even if you haven't seen them, they're in there. Fish eggs do not look like clumps of jelly.>
It was truly strange, when my daughters came to visit, I clearly pointed the new gel out and about 2 hours later, the gel was gone. I suspect a molly ate it. That is one of my questions (Will Black Mollies eat Oto eggs?). Next, some of them look ripped, as if something cut them in half. Does this rip mean they hatched ?
<Sure, the snails hatch out within a few days.>
Could a snail have accidentally ripped it when it went over this gel ? The snails are about the same size, or maybe slightly larger. I have kept a pretty detailed "fish log" and it's kind of like a diary of my observations in the tank. Apparently we started the tank 08/07/10 and added fish on 08/08/10. One phrase I used in my fish log (after discovering the Black Mollies like algae tablets and algae on the side of the tank and decorations) is "An Army of Algae Eaters". Yep, every single fish in the tank loves algae. Could be a reason why they thrive when using the 60 watt bulb until it burned out and changed to a 100 watt bulb.
<You're using incandescent bulbs? I would not recommend this. For a start, they're useless for growing plants, and they also waste a lot of electricity. But they're also dangerous -- splashing water on hot bulbs = explosion! If your hood has sockets for incandescent bulbs, I'd STRONGLY suggest replacing the bulb with a much cooler and less wasteful compact fluorescent "bulb".>
I was uneasy with the idea of causing that much algae. We still could see green areas forming on the glass, but our army usually did a pretty well job of cleaning it but couldn't clean it fast enough. We now have a 15 watt bulb. I am concerned how much algae I need to supplement.
<Otocinclus starve quite easily; if they look "hollow bellied", i.e., their bellies are concave, they're starving. Algae wafers are good, but so is blanched lettuce, squished cooked peas, sliced cucumber, sliced zucchini and cooked spinach.>
I dropped algae tablets in the tank and our original Oto never had any thing to do with them. Our Black Mollies loved them. Once we added the 2 new Otos, I tried it again and they (the 2 new Otos) love the algae tablets. So my biggest questions are concerning the Oto eggs. How do we know if they were fertilized ?
<Snail sex is complicated. They're usually hermaphrodites. Some species also have all sorts of fun stuff with 'love darts' well worth reading about.>
How can we know if they are hatched (or damaged). Are the Oto fry good enough at hiding for us to remove them before they get eaten ? And for the strangest question of all.... would it be a bad idea to move some of the Oto eggs to the tank the Black Molly fry is in ? Would she eat the eggs ? Would she eat the fry ? She is still very small (I'm guessing about 1 centimeter long). And finally How many Oto fry hatch from an egg gel ? The gels themselves vary in size as it is. My wife suggested that the gels might be mold. But they are clear.
<They're snail eggs!>
They look like they have white bubble specs in them. If we should try to setup a third makeshift tank, how important is it going to be to have a heater, filter, or airstone ? I'm sure they are Oto eggs because as a test I ran room temperature water over our largest ornament (a ceramic angel where the Otos love to hang out), and shortly later there was an egg gel near the angel. The pictures I could find online of Oto eggs are of 1 to 4 eggs and not a gel. I searched your site, and nothing quite seems to cover these scenarios. But then again, I may be a redneck, and things are always a bit different with rednecks.
<Are they? Forgive this ignorant Englishman not really having a clue what you're talking about.>
So, to make things clear, we now have 4 Black Molly adults (2 female and 2 male), 3 Otos (I believe 2 females and 1 male), and several small snails (the largest one died). In retrospect, maybe the little Oto was protecting eggs I hadn't even noticed yet ? I sure hope it's not a Chinese Algae Eater. I appreciate any and all help you can give me, thanks.
<I hope this helps. Cheers, Neale.>

FW Parasite problems (RMF?)<<>>  -- 3/30/10
Dear Crew Member
I have several niggling health/parasite problems in my freshwater aquarium. I have done much reading, much sifting through the WWM FAQs and related articles, but I fear that now the information I have gathered is beginning to diverge rather than converge, and was hoping that you might be able to provide guidance on my next steps.
I would like to begin by defending the tank itself. It is a sumped, 280L (73 US Gal) planted tank with soil underlayers in both the display and sump. The lights are timed so that when the main tank is dark, the sump is lit. Plant growth is excellent, and no fertilisers are added (as per Walstad doctrine). I have never (yes never) registered any ammonia, nitrite or nitrate in this heavily planted tank, and pH is steady at 7.5. General Hardness is 4, while KH is the only thing that fluctuates a bit between 4 and 6. Apart from the problems that I will list, the fish are vibrant and feed well. In fact I have never seen them so 'happy'. But:
<Sounds a good tank so far.>
My main concern is an aged Bolivian ram. I acquired this fish when it was fully grown a year ago. Its symptoms are flashing (focusing on the gill area), darting, shimmying, and flecks on its eyes. Sometimes its skin looks a little shredded -- white lines from the back of the head along the flank, as if it has been cat-scratched. But then this last symptom will suddenly disappear, the flashing will calm down and I am tempted to think that it has got over whatever problems it has. Except they return.
<Right. Now, ruling out water quality issues (by far the most common reason for chronic, low-level health problems with nebulous symptoms) the things to consider are toxins, diet, stress and some type of non-lethal parasite. Toxins could be things like paint fumes. Not a common problem, but possible if the tank is near a workshop or garage. Diet is generally not a major cause of problems with small community fish, but dried foods do lose their nutritional value once opened, so some care needs to be taken here. Stress can include behavioural interactions. For example, one time I kept some large freshwater gobies and had no idea why they constantly exhibited sores on their flanks. Then I noticed the Otocinclus feeding on the mucous on these fish. One thing many aquarists don't know is that Otocinclus are semi-parasitic and view large fish as moving buffets, and if hungry will scratch away at such fish, causing inflammations and excess mucous production. Finally, there are mystery parasites. Farmed fish generally come with predictable parasites such as Ick and Camallanus worms that are common in fish farms and in tropical fish shops. But wild fish can and likely often do come with low-level infections of non-lethal parasites that we don't notice and so don't treat.>
Concern number two is the five Corydoras sterbai in the tank. They will flash against the substrate.
<Typically implies irritation of the gills, e.g., by ammonia or velvet.>
These were new fish added in the second month of the tank. One of them has always had a white dusting on each flank (which I didn't notice in the shop), and a stumpy, Nemo-esque pectoral.
This dusting is not Ich, and does not seem to change or shift. But they are all feeding and growing well and otherwise happy.
<Possible velvet; would at least treat assuming it was, since no harm will be done. Salt works well here. See here:
Problem number three is a very old Otocinclus that occasionally 'furs-up'. Every two months or so it looks as if it is in the last stages of a fatal illness -- and then the next day any sign of it has completely gone. Perhaps some sort of mucous excretion here?
<If the "fur" is off-white to grey slime rather than fluffy, then sure, could be mucous. Commonly caused by what we usually call Costia, or Slime Disease.>
The other three Otocinclus are fine, fat and have grown very well.
Problem four is my shoal of cardinal tetras. They have been with me for over two years now, but currently seem to have some sort of grey-white bean-shaped (like a tiny grain of rice) parasite that sits vertically on their flanks. They flash now and again, presumably to try and dislodge whatever these things are. The suspected oldest fish of this shoal is the worst affected.
<Without a photo, it's difficult to say. Could be a Fish Pox/Lymphocystis type thing, and in itself not fatal but a sign of some environmental stress.><<More likely embedded Microsporidean colonies... common, not treatable as far as I know>>
(Might age be a theme here? The ram, the Oto, the original tetras - could this point to dietary deficiency? I feed frozen, recently opened flake food, and crushed algae and cichlid pellets.)
<Sounds good.>
It is a similar case with the marginatus Pencilfish that I acquired (about the same time as the C. sterbai) -- the same tiny flattened rice/bean on their flanks, almost as if they have swapped one of their scales for a discoloured one. Could they have in fact lost scales for some reason from an invisible parasite, rather than the mystery bean shape being the parasite itself?
Other inhabitants that are unaffected are 2 glass blood-fin tetras, 10 Boraras brigittae and 1 female Apistogramma trifasciata. The tank is also home to 2 Nerite snails, Malaysian trumpet snails, 'small pond snails', Amano shrimp, cherry shrimp, and other unidentified shrimp.
<All these invertebrates will likely be killed by copper-based medications, so be careful how you treat the tank.>
I must point out that the ram, the cardinals and the blood-fins had a similar parasite in a previous incarnation of this tank. When I added the sump, I was able to isolate them, cook them at 30'C and treat heavily with copper. Whatever it was appeared to clear completely.
<Good. However, do consider that moving them to another tank was the cure, rather than the copper. If the Otocinclus are attacking other fish, then separating them will help the victims heal. If there's a toxin of some sort in the display tank, the hospital tank can provide relief. In other words, be open minded.>
However, all plants were transferred to the new tank (despite sitting in a bucket for a week with a double dose of copper treatment), as were the shrimp, who spent time in a separate tank with the micro-Rasboras (who appear completely immune to whatever this is). Perhaps this parasite survived either via the plants, or the shrimp. Problems started again before the micro-Rasboras were added, so they can be excluded as the main cause.
I must state that I do not believe this to be a water quality or husbandry fault (apart from a lack of quarantine on my part, mistakes in transference etc). To repeat, I have never tested anything amiss in this tank, and all species should be fine within the water parameters, and with each other. There is no overt aggression in the tank. I think I introduced new pathogens either by not quarantining new stock (which I certainly will in future), or letting old ones ride in on the shrimp (or in the shrimp).
<Shrimps won't carry parasites as such, but any wet object, including shrimps, can carry the free-living stages for a period of time, perhaps a day or so.>
So unfortunately these parasites are there now -- but can you help me ascertain what they are and recommend a course of action? Already I have raised the temperature to 29'C (84'F) and have added a UV sterilizer, although this does not appear to have made a significant impact.
<It won't. UV is good at reducing the prevalence of free-living parasites, but by itself it's almost never the cure.>
From my research so far I'm thinking that it could be Costia, Chilodinella, Icthyobodo or some sort of fluke, or a combination of these -- but quite honestly I don't have a clue.
<Costia (= Icthyobodo) is a good guess for "slime disease" type things.>
I have not yet added a treatment, as most of them look to be shrimp-killers, and to be frank, apart from a bit of flashing, the fish have been generally fine. But obviously I wish to eliminate the pathogens from the system, and the ram's discomfort is evident enough to now be worrying.
In terms of stages I would like to 1) try temperature raising to 30'C and UV sterilization
<Warming the water can speed up the life cycle, but it can also stress certain fish, so balance the two things.>
2) perhaps (although I'm not keen) try adding salt (would this help if it were flukes? -- opinion seems divided)
<Salt is a low-risk approach for treating Velvet and Ick. To treat Costia requires high salinity dips and a somewhat higher salinity in the tank, so while low risk in itself, it has to be done properly. Salt water dips can help treat flukes. Do read here:
3) trying a shrimp-friendly anti-parasite medication (Praziquantel -- if I can get hold of it here in the UK)
<Yes, you can get this from a vet. I would treat the fish in a hospital tank and leave the tank fallow for a while. Alternatively, keep at least some shrimps and snails in their own tank in case the ones exposed don't survive.>
and finally the last resort of 4) resorting to a formalin and copper-based medication.
<The nuclear option!><<I would NOT do this>>
Other options I have considered are moving the shrimp to a spare 40L tank and treating the main tank. However, what would I do with the shrimp then?
<Once isolated for a few days, shrimps shouldn't carry any viable fish parasites at all, provided they really are isolated. That means taking care not to mix nets, buckets or anything else that could bring more free-living parasite stages into the shrimp tank. Do review the literature here at WWM re: treating marine whitespot in reef tanks; essentially you're doing the same thing here.>
How long would they have to be in isolation to be guaranteed parasite free?
<In theory things like Ick can live without a fish host for a day or two, but in practise you want to leave the tank fallow for a couple of weeks at least. Again, refer to the marine articles on this topic.>
Alternatively, do I cram all the fish (if I can catch them - Sheesh I do not look forward to that afternoon) in the 40L, blitz them with heavy meds and leave the main tank and shrimp fallow?
<Could work, though 40 litres would be a bit tight. Try using 5 gallon buckets with lids if you need extra "tanks". If you add a heater and filter of some sort, these can work fine for a week.>
Would this work or will the pathogens hide in the substrate?
<They can't hide indefinitely, and there really is an expiration date of sorts on the free living stages of most parasites.>
This tank will one day become a reef tank, so avoidance of copper in it would be preferable.
Any insight you can offer would be much appreciated.
<Hope this helps.>
I apologise for the length of this query. Let me finish by saying that WWM is by far the number one web resource I know of for problem solving - I have used it to research two unrelated issues already, with excellent results. Your generosity with time and information is, quite frankly, no less than a credit to humanity! So big thanks.
<Kind words indeed. Cheers, Neale.>
Re: Parasite problems (RMF?) -- 3/31/10
Hi Neale
<Hello Joe,>
Thank you for your excellent, attentive response. I am enlightened on several issues, and corrected on my diseases! I hope you don't mind me coming back at you with a couple of points/queries.
<Fire away.>
Firstly, I've read your article on salt use, and I will give it a try, on the basis of treating velvet. For optimisation, I assume I keep the UV sterilizer on at this stage?
<Can't hurt.>
Secondly, I did not know that Otos could go that way. I have not observed this behaviour (despite occasionally observing the tank at night with my rear bike-light), but will remain vigilant. When this condition was previously 'cleared' the Otos were in the same tank as everyone else - so I think they might have an alibi on this one.
<Not saying the two things are connected, but I wouldn't trust Otocinclus, period, and that's based on witnessing the havoc they can cause.>
Thirdly, I am sorry to say that today I noticed that both the Apisto and the blood-fins have now started flashing. I am certain that they try and scratch their gills. All of them - they are all trying to scratch their gills - it is gills, gills, gills - this I would strongly bet on. So from what you wrote I would assume that you would think this is indicative of either a) ammonia b) a toxin or c) velvet?
<You can't tell which of these. So has to be a process of elimination. Test for ammonia; consider possible toxins; treat for velvet.>
I feel confident I can discount ammonia - as soon as a problem arises my tests kits get used - sometimes several times a day, sometimes late at night. I use different test-kits, and have the water tested at different fish shops. Never anything amiss.
Regarding toxins, I (and my family) are very careful around the tank, concerning cleaning products etc. I would have thought that if there was a toxin in there, all fish would be immediately irritated, rather than this progression of irritation, that is currently leaving the micro-Rasboras unaffected.
<Yes and no. For example, air-breathing fish (like Corydoras) are going to be more sensitive to airborne pollutants than other types of fish. Then again, some fish are intrinsically more resistant to poisons than others.
To give a textbook example, among marine fish Opsanus tau is famous for being able to live and breed in harbours where virtually everything else has gone. So there are shades of grey here.>
When I added the fish back to the tank (after their stay in a holding tank where they were treated) there was no sign of any flashing for a few weeks - possibly even nothing before I added the C. sterbai. Is there any other avenues I could pursue to discount a toxin being a problem?
<Could be air, could be errant children (not to be ignored, this, how I lost my first goldfish as a boy), and also things in the tap water, e.g., chloramine if not treated for, or copper, if not treated for.>
I worry there isn't. As a long shot, could smoking (in the garden) and then feeding fish somehow put toxins into the water?
<Can't see how.>
But again I would expect a non-gradual progression of irritation - blanket irritation if you will, rather than this flashing behaviour moving slowly from fish to fish. What do you think on this reasoning?
<Yes, it's what you'd expect. But the thing with biology -- as opposed to the other sciences -- is that there are always exceptions.>
So I will try the salt approach at 2g/l. While I have you Neale - this is probably a no-brainer, but do I go with cheap table salt, or should I give them some Maldon?
<If using salt from the grocery store, then I would use, and have used, rock sea salt or better still kosher salt (which doesn't have any additives at all). But ideally, use aquarium/tonic salt -- not marine salt mix. The cost difference will be trivial, and perhaps worth it for peace of mind.>
Thanks again
<Cheers, Neale.>

Tiger barbs and Otocinclus I just brought home 3 Otocinclus and 1 twig catfish for my 29 gallon tank containing 4 tiger barbs.  The tigers are ganging up on the Otos and chasing them all over the tank.  I am worried that the stress will kill them!  They have not spotted the twig cat yet but I have just read that the twig cat is easily harassed.  These are the fish that were recommended by the aquarium store (Old Orchard Aquarium in Skokie, Illinois) knowing that I have the barbs.  I was going to buy a clown Pleco having read up on them.  The guy in the store said they were not good algae eaters and to get the twig cat instead.  I am ticked!  I don't want these fish to suffer but what if the store won't take them back tomorrow? <Hello, Tiger Barbs sure can be terrors.  If you provide plenty of cover and dark hiding places they should be ok.  Live plants are great.  If the tiger barbs do not ease up on them after a while you may want to consider removing the Otocinclus.  Please be sure that there is enough food to go around for the Otos and the twig catfish.  Have you checked out the article below, good stuff.  Best Regards,  Gage http://www.wetwebmedia.com/FWSubWebIndex/otocinclusart.htm>Otocinclus I just got a little Otocinclus which I planned to put in my 25 gallon aquarium. The aquarium has 2 goldfish, one a solid 5 inches long and the other smaller, maybe 4 inches long but most of which is a fan tail. I put the little Oto in, and got quite worried that they might eat him. This morning I found him in an impossibly small corner, just barely under water, where they could not get him.  My question is, should I take him out and keep him elsewhere until he is larger or will this always be an issue. Alternatively, will he be a good hider and I will be able to stop worrying. <The Oto really isn't a good fish to go in with Goldfish. The goldfish like cooler temps than the Oto and the Oto stays small enough that him getting eaten is always going to be a concern. Your best bet is going to be to put the Oto in a separate tank or return him to the store.> Also, the pet store said that one Oto would be fine, but I read this morning that they should be kept in groups. What is your advice? Thanks! Carol <They are much happier if kept in groups. Ronni>

Firemouth Bit Off More Than He Could Chew I tried throwing some Oto's to clean up in my cichlid tank. A few days, all was well, but yesterday morning I see a tail sticking out of my Firemouth's mouth. Nothing I hadn't seen before, except that the tail end was still sticking out last night, and this morning as well. I just got home from work and he still hasn't been able to swallow it down. I thought of netting the Firemouth and trying to pull it out, but I figure that I can end up tearing up his throat. He doesn't seem overly stressed about it, and has even kept up his harassment of a larger jack Dempsey in the tank. I believe he was even eating some of the flakes I threw in earlier. Having been at least 36 hours, what should I do? Keep waiting and hope he eventually gets it down, or try and pull it out even though I may do a lot of damage? Anyone else have this kind of problem before? < Unfortunately, Oto's like most catfish have stiff spines that they use for protection from predators. I would take him out and get a good look at the mouth. I would be tempted to take a pair of small scissors and cut the spines on the Oto and extract the body. Then use tweezers to extract the spines. If you can't pull them out then I would push them through and pull them out from the other side. Not often but it happens.-Chuck> 

Otocinclus question ... plants/comp.    3/18/06 I have several Otocinclus catfishes in a 46 gallon freshwater tank with 2 Gouramis, a couple of tiger barbs and 2 clown loaches.  Just last weekend I purchased several nice Amazon plants and to my dismay they seem to be getting little holes in the leaves, about the size of the Otocinclus' mouths! <Ah, yes>   Could they be the culprits, I haven't seen any other of the fish hanging around the plants? <Could be... but also the barbs, loaches... however the Otos are most likely at play here> I found reference to them needing plants around but I wasn't sure if that was for hiding places or to eat. <Mmm, both and more. Bob Fenner> Thanks, Olivia

Otocinclus and Comet DON'T MIX! EMERGENCY  07/21/06 Hi, love your website, thanks for it, but I have a huge  problem!! <<Hi, back. You're welcome. Let's see what we can do. (Tom here, by the way.)>> I woke up today to find my Comet munching on my Otocinclus! Actually, what I mean by that is that the Oto was lodged in his mouth with about 25% of it sticking out. He doesn't appear to be choking because he is still breathing. <<I assume you're referring to the Comet because the Oto doesn't sound to be in good shape.>> I got two new Oto's a couple days ago and since then they've both been lethargic with clamped fins, each was tiny, 1 inched guys and my Comet (Harry, don't ask) is about 4 inches long excluding his tail. He's always been greedy and   I think what happened is the Oto died and the Comet finally could catch him and did. <<Not unusual for Goldfish to do this. They tend to be "opportunistic" feeders and your Oto gave Harry the chance he was waiting for...unfortunately.>> No search engines helped me at all! <<In fairness, it's not the typical inquiry.>> At this point, Harry is moving slowly and keeps sucking or blowing his mouth, I can't tell which. This is a major problem and one way or another might solve itself before you answer back, but right now my main concern is lack of ability to eat or transfer air in the swim bladder, and of course lodging it in more and choking! <<As long as he's moving water over his gills, he's not "choking". He may not be very comfortable but he won't suffocate.>> Just in case he lives and for future references please help! I tried using metal tongs and I grabbed the protruding tail but I couldn't get it out, I'm sort of nervous of pulling too hard. How do I dislodge it, or can he digest the head soon enough and eventually pass it through?? (I seriously doubt it though.) <<I seriously doubt it, too. Goldfish are primarily "vegetarians". Their systems aren't developed for dining on other fish. Likely the dorsal rays are getting caught in Harry's mouth as you try to pull the demised Oto out. You might try twisting the Oto one way, or another, to get the rays to "release".>> And should I remove my other Otocinclus and my (very lively and quick) Algae eater? <<First, if by "Algae Eater", you're referring to a common Plecostomus, I wouldn't worry about this. Harry isn't likely to be interested in a "lively and quick" tankmate. My concern here, without getting on a soapbox, is that many Otos are "captured" in the wild by the use of cyanide. I have no direct knowledge of these fish being bred in farms, though it's entirely possible that they are. In any event, the fact that both of yours showed signs of lethargy and clamped fins indicates, to me, that it's possible that they were taken with cyanide, a chemical that will, unfortunately, stay in their systems. Otos, regretfully, show an inordinate amount of "infant mortality", meaning that they often die within hours, or days, of being introduced into the tank. Fish that feed on the dead fish are going to be ingesting cyanide if the deceased fish contain this in their bodies. My recommendation is to get the Oto out of Harry's mouth regardless of what it takes and remove the other Oto from the tank. Easier said than done, I know, but you must do this.>> Thank you for your time, and sorry my email is so long. This is my first major goldfish problem and I'm very anxious. <<Not to worry. You're more than welcome and I completely understand. Tom>>

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