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FAQs on Otocinclus Reproduction

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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.>

Water Babies! (Otocinclus) Hi guys! Me again! <How cool is that.. I'm still me too <wink>! Anthony> My tropical tank has now been up and running for five weeks! The algae ****problem has been solved with the addition of the Otos (thanks for the tip, Anthony!)  <don't thank me...thank those wonderful Otocinclus catfish...hehe> Two weeks ago I added a pair of dwarf Ram Cichlids.  <lovely but shy creatures> On Tuesday (26th) I watched as the female laid eggs on a leaf and the male fertilized them - fascinating!  <you have been blessed!> The male now seems to guard the eggs while the female swans off around the tank (if only this was the case in the human world). <you do recall that this is a male dominated hobby, my dear? hehe... try to sell this one to the union! Ha!> Anyway, I was wondering how long it would be before the eggs hatched.  <a matter of days dependant on temperature> I have read quite a few books but nowhere does it say how long it takes for the eggs to hatch. Also, do these fish guard their fry once hatched or are they left to their own devices? <no...parental guarding, but don't expect much in a community tank.> Also, I appear to have a few baby fish in the tank which have mysteriously appeared!  < a livebearer no doubt> These babies look suspiciously platy-like but on reading your FAQs and articles I understand that platies get fat and go transparent in their vent areas before giving birth. None of my 7 platies are or were fat and none of them appeared to have transparent areas. I certainly did not see any baby fish eyes inside them. I have had the platies for four weeks and these babies are coming from somewhere!  <if you don't have another live bearing species it was one of the platies> Currently, they are hiding in the moss and I am trying to feed them using crunched up pellets, crunched up flakes and frozen and live daphnia. Not surprisingly, they are not terribly forthcoming at feeding time. Is there anything else I can do to help them survive?  <short of separating them, bushy floating plants (plastic or live)> I am aware that they may not live for very long in a tank with greedy platies and guppies! I think my cardinal tetras are the only fish not big enough to eat them! Finally, survivability issues aside, I am wondering if overcrowding could become an issue (depending upon the number of survivors - I include both the platy babies and potential rams here). Do I have to keep getting bigger and bigger tanks each time I become a parent?  <if you don't eat fish, you do> I can see the little dears eating me out of house and home in no time! <you may want to be more selective about the sexes... remove a gender as it were <boo>> My aquarium is planted but I will be getting some more plants (hopefully water sprite) this weekend to add additional hidey holes for the new arrivals. Any information you could provide regarding my babies would be much appreciated! <yes... build a 400 gallon tropical fish pond in your basement <wink>> Many thanks! Lesley <quite welcome. Anthony>

Otos... Dear Crew, A little question  about the likelihood of the Otos in my planted freshwater tank breeding.  We have a four foot Juwel tank planted, with 6 Corys, 6 black widow tetras, 11 cardinals, 1 Sailfin Plec, 1 ram (we did have 3, sadly they were not healthy fish!), <Yes... the tank bred ones are proving less hardy than wild-caught in recent years> 4 red claw shrimp, and as far as we knew, 6 Otos, 2 flexilis, 4 affinis...except, yesterday, while doing a water change and gravel clean I noticed a very very small affinis, now I know that ours were all bigger, so is it likely that we have had babies? <Sure seems like it> I can't think of any other explanation apart from the catfish fairies! <Ha!> I thought that it was unlikely for them to survive in a community tank? <Mmm, too often, yes... but yours sounds like just the ticket> our water temp is 75-77, our ph between 6.5 and 7, we have very soft water 1-2 dKH (we top it up to keep it there, otherwise it drops lower), so have we magically done something right? <All the way around, yes> Thanks for any thoughts you might have on breeding Otos... Cheers, Nicola <Congratulations. Bob Fenner> Nicola Blay, BSc, MSc International Zoo Veterinary Group

Query pregnant Oto  11/16/05 Hello, I read your article online and was hoping you can help me.  Up until I read your article today, I had only read that Otos did not breed in captivity. <Rare, but has happened> I was quite concerned, therefore, when I saw one of my Otos looking "very" pregnant...or deathly ill.  I have a planted 60 gal tank, 2 fancy goldfish, 5 Otos and too many fancy guppies. The tank is around 24*C, 2 large driftwood, lots of plants including a huge lily with leaves averaging 6+ inches diameter. <Neat!> Water parameters very good. None of my fish have died or been ill for over 2 years. All five Otos were purchased approximately 14 months ago. I have a grave concern that either my Otos is horribly diseased with something... or pregnant. I don't know which so I am hoping if I describe her to you, you may be able to tell. <Okay> The other 4 Otos have not altered in either appearance or behaviour. Lately one or two of these "healthy" Otos are literally side by side or nose to nose with the Oto I am concerned for. <Are social animals, but...> While the Otos often roam/sit together (within a few inches to 1 foot) I've never really noticed this closeness to this degree. I am concerned they know something is wrong with her or, best case scenario, they are a mated pair. Sick/pregnant Oto appearance: Normal sized round/plump whitish tummy now hugely distended. Looks like a round small marble of approximately 3/8's of an inch in diameter. Tummy definitely round, neither oval nor flattish. Red streaks appear in the formally white area of her underside and tummy, including near face/jaw/mouth. <The reddening may be trouble> Sick/pregnant Oto behaviour change:  * Once saw her hanging onto driftwood (vertically and right side up) with just her mouth and tummy about 1/8 inch from driftwood  * Sits "on top of" a particularly flat sitting (underwater) lily leaf. The leaf is about 6-8 inches in diameter but she seems more interested in just sitting/sleeping there than eating on it. While she's there one other Oto seems always there as well. * While the Otos go everywhere in the tank, the length of time she spends just sitting there is unusually long and the fact that the other Oto is there is very unusual. * The red streaks scare me and even her eyes look reddish and/or distended?? <Not good... not normal reproductive change> Sick/pregnant Oto behaviour non-change: Still busily munches on algae and driftwood.  I would greatly appreciate your opinion, references and help. Thank you, Eileen Reid <You will soon know... the very round appearance should not persist more than a week... the female will lay her adhesive eggs, with one or male present, and they will provide some guarding behavior, not moving much, for four or so days until they hatch... Bob Fenner>

Re: Query pregnant Oto, Net Virgin  11/17/05 Hello, I read your reply. Thank you.  This is the first time I am using the internet for this so don't know how to reply/ask more questions. <This is fine> The Oto is still alive. I picked her out of the aquarium yesterday. She didn't struggle at all which surprised me. <Me too> I just gently picked her off the side of the glass. I held her in my hand an looked at her really closely.  She has clear fluid inside her tummy. It's as though clear fluid is surrounding her internal organs. Her scales do not stick out. The Red area seem more localized at the bottom part of her tummy, and I would say, out of the water, the "round marble" is actually more of a "flattened" marble. If she is not pregnant, can you think what could be wrong? <Could be Ascites from some cause, or dissolved egg mass... or?> or is there anything I can do besides waiting? <Perhaps adding a level teaspoon per five gallons of system water will help "move" whatever this is> I put her back on a leaf and she swam onto another area. I checked on her this morning, and she's still alive (and had move to another plant).  If she is ill and she dies in the aquarium, will whatever she has pass to my other Oto's and Goldfish? Thank you, Eileen <Not likely. Bob Fenner>

Re: Query pregnant Oto  11/22/05 Hello Robert, Well, she's still alive and still looking much the same, so I doubt she is pregnant. The one bad thing in addition to everything else is, it appears the linear stripe down her side is faded and is now almost non existent. On the bright side, she is still eating and none of the others have her appearance. I'd say the other Otos have changed in that the one always around her is no longer at her side. <Not pregnant... egg-laying... for this long> I am hoping she'll get better. I looked up "Ascites" on the internet, and the more I read, the more I think this is correct. I could put her in a little container to: "<Perhaps adding a level teaspoon per five gallons of system water will help "move" whatever this is>" A few questions: -what is it I should add? <Epsom Salt... aka Magnesium Sulfate> If I segregate her into a little container, will she die from shock? <Better to treat all... in place> And what about light/heat.. how much? <Would not change these> Should I give her a plant or something? <A good idea.> At this stage, do you think there's any hope of the fluid leaving on it's own? <Oh yes> Thank you for your help, Eileen <Welcome. Bob Fenner> 

Re: Query pregnant Oto - 11/25/2005 Hello Bob, <Actually, Sabrina here, in his stead; he's out of the country for now.> Thanks for your help.  Unfortunately she died last night.   <I am so sorry to hear this....> I saw her on a leaf earlier in the night, then saw her upside down (still bloated) on the bottom.  I picked her up and to my surprise, she struggled a little. I put her back on a leaf, but soon after she tumbled down again and lay upside down. I left her till very late, then thought I'd check again since she hadn't moved. She had died. <My deep sympathies to you.> Would you have any idea what caused this? <There are many possibilities, here.> Everyone in the tank still appears okay, and as I said before, I got all the Oto's over a year ago, so whatever was wrong, it had to come from me. <No, actually, this could have been something a long time coming....  no need to put blame on yourself, here.  Bloating like this often happens as a result of internal bacterial infection.  Bacteria that cause such infections are often present constantly in aquaria, and only actually become problematic when a fish has a depressed immune system.  An injury, a genetic weakness, a disease the animal has been fostering for some time (Mycobacteriosis, for one example) all can cause such a thing to happen.  It is unlikely that this was a result of anything you did or didn't do.> Once again, thanks for you quick replies and expertise. <And thank you, very much, for your correspondence.> Happy Thanksgiving! <To you and yours, as well!> Eileen Reid <Wishing you well,  -Sabrina>

Tiny White Bugs in a FW Set Up  - 03/25/2006 Hi.  I have a question that I haven't been able to find an answer to.  I have a one gallon tank that I keep on my desk that has a Betta and 2 Otos.  I've had the Otos for about 6 months.  I put some shells in the tank a couple of months ago and the two Otos have been hanging out under one of them a lot.  I noticed a week or so ago that one of them looked a little plump, but I had been told it was very unlikely they would ever reproduce (I didn't really want them to).  Last night, I noticed that the plump one was more than just plump, it was huge.  I then noticed dozens of little white specs moving about the tank along the bottom and the sides.  I was worried that I had some kind of infestation, but the specs moved in the same way as the adult Otos-- very jerky, swimming to the top occasionally-- so I assumed they must be fry.  I removed the Betta.  I noticed a little while later that the larger Oto was floating, dead.  It looked like it had blood in its abdomen. My question has to do with the little white things.  Are Oto fry really THAT tiny?  Or is something else growing in my tank?  I searched the internet for answers but it doesn't seem like many people have much luck breeding them.  I scooped up a few and took them to the pet store, but they were so tiny no one could tell me for sure what they were. < Your Oto's died from an internal bacterial infection. The tiny white bugs are probably a form of daphnia that came in with the sand or even a plant. It can be treated with Fluke-Tabs.-Chuck> If you don't have an answer either, that's ok.  I'm going to have to break down the tank when I move out in May, so whatever they are, they probably won't survive the move.  I've attached a couple of photos I took. Thanks Andrea Hall <<To RMF these do appear as fish fry... I would not be so sure that these fish did not reproduce. RMF>>


Breeding Otocinclus ... Neat!   6/22/06 Greetings, and thank you for your site, it has a wealth of information. I was particularly excited to see a letter from Andrea Hall entitled "Tiny White Bugs in a FW Set Up  - 03/25/2006" in the "FAQs on Otocinclus".   I don't have a question for you, but rather I'd like to make a comment about that letter and relate an experience of my own. Andrea expressed concern over some little white specks she had discovered in her tank when examining her Otocinclus which "was more than just plump, it was huge" and had submitted photo's of her Oto and the specks.   One reply from Chuck suggested they were probably a form of daphnia, RMF suggested that they indeed were likely to have been fry.   I had an experience with my two Otocinclus this past weekend which would confirm that they are indeed fry. This past Saturday my wife mentioned to me that she had noticed the previous evening that the Oto's appeared to be spawning, I took a look and found that it seemed they were, the female's belly was extremely distended - probably two to three times its normal size. The male who normally paid little to no attention to her was frantically following her around the aquarium. As she seemed to stop and clean a spot of glass or a plant leaf he would cling to her or next to her, sometimes wrapping his body around the top of her head so the two of them formed a "T" shape, and sometimes clinging to her back or side.   Searching the internet I found precious little in regards to Otocinclus spawning, but I did find that the behaviour was supposed to be a fairly common mating routine among their relatives. So I assumed that they were breeding. The behaviour continued for many hours.   The following day the females belly was back to her normal size and the two were back to their normal routine - eating, resting, and pretty much ignoring each other. I tried to find eggs in the tank but was unable to see anything. While looking for eggs though, I found the same little white specks throughout the tank as Andrea described, they were everywhere, numbering easily in to the hundreds. And, as Andrea described, they moved much the same as the full-grown Oto's.  I too, thought they may be some kind of invader in my tank, but found the coincidence of their arrival and my Oto's deciding to spawn just a bit too convenient. So assumed they were fry. Then today I ran across Andrea's photo's on your FAQ page.  My fry look exactly like her white specs.   I'm just as shocked as I am excited, this is a small five gallon tank that I keep slightly brackish for the sake of the green spotted puffer who was it's sole occupant until putting the two Otocinclus in to eat the algae about three or four months ago. I felt bad about putting them in that tank, feeling the salt content may be to high for them, but they have thrived and by this recent sequence of events I'd judge them to be quite content in their home. Incidentally, the salt content is about 1 teaspoon per gallon, half of which is aquarium salt and half marine salt.  I am sending you links to video I took of the spawning and of the fry. They are quite large videos not too suited for dial up connections, and even on high speed will take about a minute to load. If you'd like links to video more suited to dial up let me know and I will make them available.  Link to breeding video : http://www.farrant.info/video/Otocinclus_breeding.wmv Link to video of fry : http://www.farrant.info/video/Baby_Otocinclus.wmv I'd be very interested in any comments anyone may have, and very grateful to any tips anyone may have to help me raise the fry successfully. I have rounded up any plants and algae laden materials I could find from my other tanks to help supply them with food as well as making a broccoli paste for them. The puffer is getting moved to a different tank, I have turned off the filter so their pinpoint bodies don't get sucked in - to help compensate I have increased the airflow in the tanks bubbler and am doing daily trickle water changes with aged water.  Thank you, Bill Farrant < One of the great things about the internet and this website is the information that gets passed around. Oto's are very cheap algae eaters than many breeders have no interest in breeding because there is no money in breeding them. That is why you have had trouble finding any info. In the previous letter you referred to, I was unable to bring up the photo and wrongly assumed they were daphnia. Bob was able to get the photo up and posted on the website. I looked back and saw the photo and knew that they were fry. This information is very useful because there are many other Oto species that are very attractive but very expensive too. Breeders may be willing to obtain these new species if they knew how to breed them. Thank you very much for sharing this info.-Chuck>

Bloated Oto  3/23/07 Hi Guys: <Patrick> I have an Otocinclus that is bloated. He has a bulging belly as you can see in the pictures that are attached. Problem is he is not eating the algae from the tank. Has not been eating for quite a while (a couple of weeks) We thought he was eating excess fish food so we have cut that back and he is still as large, maybe getting larger but not eating the algae. Could he have a blockage? <Yes> We had a clown Pleco that ended up doing this too, getting bigger but not eating algae till we found him dead. <Mmm, what sorts of food/s are you feeding?> Do you suspect constipation?  I tried peas but he hasn't eaten them at all.   Bacterial infection?   <Possibly> What do I use.  One guy suggested Epsom salts, <I do too... safe, often effective... readily available> what levels in what amount of water.   <Posted: http://www.wetwebmedia.com/FWSubWebIndex/saltusefaqs.htm> I can move him to an alternative tank to set up a hospital tank. thanks for your help P. Carty <This fish may also be developing eggs... perhaps be egg-bound... I would try the Epsom per WWM. Bob Fenner>
Re: bloated Oto   03/23/07 As per the web page I will put an additional 1/2 teaspoon of Epsom salts to my 10 gal tank (I added 1/2 teaspoon yesterday).  Some additional information that may or may not bear on this issue.  I bought test kits yesterday and did testing of Nitrates and KH hardness.  Nitrates are at 80ppm and hardness at 10. <Yeeikes, both high...>   I have started 15% daily water changes with Reverse Osmosis water.  My goal is to reduce nitrates to 20 or lower and hardness to 7 (as per pamphlet that says tetras like it around 7. <Ah, good> Would these two high values have any bearing on the bloating of the Oto? <Oh yes... of a certainty> You had asked what kind of food I was feeding them when I mentioned our late Clown Pleco.  We are feeding TetraMin tropical flakes. <Mmm, I would augment this with either some other prepared food/s or give them a "treat" of some frozen/defrosted meaty foods at least once a week> Thanks again for your advice. <Welcome! Bob Fenner>

What do I do with extra Otocinclus?  5/30/07 I have a 5 gal. Eclipse Corner Tank on my desk at work. There were 2 Betta's (with a divider) in it, but when I added 3 Oto's from PetSmart soon after the Betta's died of tail/fin rot. I moved them to separate bowls, and treated them but they died. I figured it was the addition of the Oto's so I expected them to die as well. That didn't happen. They cleaned my tank of all algae, and I feared they would have nothing to eat because it seems they won't eat the algae flakes. So, I went to my buddy's Cichlid tank and traded all the ornaments (no, I don't know if this was a smart thing to do or not, but I did it anyway). It seemed, that this brought new life to the Oto's, as very soon after I spotted little white things on the front of the tank. When I realized it was fry, I shut off the filter. I counted about 12 fry stuck the glass. I turned to the internet for advice and found little. I put a baby sock rubber banded over the filter intake and turned that back on. Added an air pump for them. I fed them boiled spinach leaves. Well, a spinach leaf from a coworkers salad stuffed in a cup of hot water. They ate little holes in that overnight. I do a 50% water change weekly, and slowly suck out the leftover food every few days to keep the substrate somewhat clean. Now I keep exchanging plants with my buddy's Cichlid tank for food and they clean it overnight. There are now 4 or 5 baby's left and they are half the size of the adults and seem to be doing fine. My question is, what can I do with these extra Oto's? Can they go in the Cichlid tank? Isn't that too much hardness for a Cichlid? Or can I support 7 to 8 Oto's in a 5 gal tank? PetSmart told me that they stock the same sex in the same tank and sell them that way so this wouldn't happen. Well they screwed up and now I have these new guy's. What do people do with their new fish when they didn't mean or even know they would spawn? <Wow. This is quite an amazing tale! On the one hand, a 5 gallon tank is really too small for Otocinclus. As a group, Otocinclus are considered "delicate" because they need good water quality and lots of oxygen. In most community tanks, they tend to be short lived. But yours are doing well, so well done! Anyway, as to where to put the Otocinclus. I personally wouldn't mix them with anything other than, perhaps, South American or West African dwarf cichlids. The problems are multiple. Firstly, yes, they will not do well in Lake Malawi/Lake Tanganyika type aquaria. Such hard and alkaline water conditions will not suit them at all. Secondly, when kept with slow moving things like angelfish and discus they tend to suck the sides of the bigger fish, scraping off the mucous. I've seen this in my own tanks, with the Otocinclus rasping away on large gobies, creating nasty blisters. Aggressive fish like convict cichlids will simply hammer them to death. So ideally, give them to someone with a peaceful community of other small fish such as barbs and tetras. PetSmart cannot possibly sex Otocinclus so their advice there was nonsense. In fact, breeding Otocinclus is quite uncommon, so you've actually done rather well.> Tom <Cheers, Neale>

Otocinclus <maybe Danio> fry, fdg.   6/30/07 About a week ago, maybe less, I had my husband remove a few plants that weren't looking so hot from one of our aquariums. He thought something along the lines of putting them in a bucket and seeing if they would look any better (It couldn't hurt) <Ahh... a good friend grows such plants almost year-round outdoors here in San Diego... spectacular results> So they were outside in a bucket...some morning sun, nothing too harsh. Tonight he was going to put the plants back in the tank and dump the bucket... being always worried about Cyanobacteria and such I bent down and peered real good at them, and noticed a tiny movement. We have some incredibly tiny fry. I have never seen any fry this small... the only breeding fish I have are angels and guppies I guess. But the tank these plants came from had: angels, serpae tetras, Columbian tetras, neon tetras, zebra Danios, Otocinclus cats and a pair of Cory cats. <I see...> After looking at someone's video of fry, it looks like they may be Oto fry... very very tiny, almost invisible from the side. So they are in the hospital tank now, along with the plants from the bucket and in the water that was in the bucket... we had heavy rains today and the bucket overflowed. We have about 20 fry left. What should I try to feed them. <"Infusoria" would be ideal... see the Net re... But a pre-made commercial food prep. is the only thing practical here. See the Net, your LFS re such... "tube food"...> I thought of rotifers since they are tinier than baby brine shrimp, but if they are Otos it would seem that wouldn't work at all. I also have a package of Hikari first bites that is as fine as talcum powder and contains many things, among them Spirulina, milt meal, along with some krill meal and such. <The liquid "tube food"... egg-yolk based...> I'd hate to see them die, especially after the miracle of even seeing them to begin with. Any ideas? If I put a hulled pea in there would they nibble on that? The plants have a little algae on them as well but the fry are so darned tiny... Julie <Might be the Danios otherwise... Oh, and congrats! Bob Fenner>

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