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FAQs on Otocinclus 2

Related Articles: OtocinclusLoricariids

Related Catfish FAQs: Otocinclus 1, & FAQs on: Otocinclus Identification, Otocinclus Behavior, Otocinclus Compatibility, 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

Deworming zebra Otocinclus question      12/24/17
<Hello Andrew,>
I recently got 4 zebra Otos, from 2 different stores. They have been at the store at least a month (some of them have been there for two months).
They're not super skinny but not super fat either. Given this I suspect they don't have any overly severe issues, but my default assumption is that wild fish like these will have some sort of intestinal parasites.
<While that's possible, the biggest source of mortality with Otocinclus is plain old starvation. These are small fish, and like other small fish, probably have enough body fat (or however fish store energy) to easily last a couple weeks. Beyond that, they're in starvation mode. This matters because from the point of capture to the day they're introduced to the home aquarium can easily be months, and in that time they're usually not getting anything close to sufficient green algae and micro-invertebrates to keep them well fed. So while there's no harm -- and probably some benefit -- from the standard issue PraziPro de-worming treatment, I'd be more worried about getting them to eat properly. A bright light over the tank, ample green algae, plenty of oxygen, and lowish temperatures (22-24C/72-75F is optimal) are the order of the day here. If you don't have sufficient green algae -- and that's the algae they need -- then good quality algae wafers, such as those from Hikari, do the trick nicely.>
For now I have them in their own 5 gallon tank where I can easily observe and feed them.
I have seen it suggested that Praziquantel followed by Metronidazole is effective. Does this sound like a good protocol?
<Yes, though any particular reason you want to use Metronidazole?>
How long should the treatments last?
<Do follow the instructions on the packaging. Combining medications is possible if the manufacturers state it is, but honestly, unless dealing with a critically ill fish, I prefer to handle things in a more organic way -- start off with optimal diet and living conditions; if warranted, de-worming; and only if the fishes were still not responding positively, would I break out the antibiotics and/or Metronidazole.>
I have not had good luck in the past with getting fish to eat medicated food.
Thanks, and a happy holidays to the team,
<And to you, enjoy your winter solstice festivities! Cheers, Neale.>
Re: Deworming zebra Otocinclus question      12/25/17

Hi Neale,
Thanks for the response!
<Most welcome.>
There's no particular reason I want to use Metronidazole, other than that I've seen it suggested. My guess was it may help with some parasites that Praziquantel may miss.
<Possibly. Metro is primarily used (with fish, at least) for Hexamita and other protozoan parasites.>
But based on your comments I'm guessing it's rather harsh on the fish?
<Not aware of any specific problems in all honesty, and Metronidazole is often used with quite sick fish when nothing else will help. It's more a cost/benefit thing, in my mind. Look at it this way: Otocinclus are inexpensive, and if you buy ten, and one or two die, but the others sail through quarantine and fatten up nicely, that's going to be a lot cheaper than buying a smaller school of Otocinclus and medicating with PraziPro and Metronidazole with the aim of ensuring all of them survive. No guarantees, mind, either way! But with small, cheap fish, I'm more minded to buy slightly more than you want, fatten up with optimal diet/environment, and then see what happens before medicating.>
Thanks again,
<Welcome. Neale.>

Otocinclus      7/4/16
Hello there,,
Should I be worried that my Oto is this big?
<I would be concerned yes. Could be a few things amiss here... water quality, foods... Please read what we have archived on the genus on WWM. B>
I heard they don't breed in captivity, so is it getting fat or is it ill?
Chante Herbst

Oto, no rdg. as usual    12/3/14
I decided against the bandit Cory and got an Otocinclus catfish instead. It will grow to about 2 inches. It requires a 10 gallon tank.
<Read here: http://wetwebmedia.com/FWSubWebIndex/otocinclusart.htm
and the linked files above. B>
I have a tank rated for 29 gallons by the manufacturer. The tank is 36" L x 12" W x 18" H. The ph is 8 and nitrates and ammonia at 0. My filter is a sponge filter rated for 40 gallons. This tank contains 2 guppy females, 5
neon tetras, 10 platy fish, and numerous bladder snails. According to
internet aquarium stocking sources I should have 36 inches worth of space
for fish stocking.
With the Otocinclus I will add, will I be overstocking this tank? Thank you.

Otocinclus question - 05/11/2012
Hi crew!
WWM: Hello,
Grr it's finals week, and here I am adding to my stress worrying about my new Oto which I introduced to my tank a week ago. So I have 3 Otos, they are all brown-silver with very white bellies and a black line dividing the middle ( sounds like all other Otos doesn't it?)
WWM: Yes.
the newest one looks like the other ones in every single way except for its tail. whilst the other two have clear spot patternings on their tail fins(2 small ones at the base and a larger clear patch near the edge), the newbie's tail fin is colored black along the rays (or I think they are called rays?). He never schools with the others, and seem positively dead during the day. My Cory will bustle past sending a shower of sand on the newbie - if he's lying on the sand. And he wouldn't budge an inch. other times he finds a nook somewhere and stays there for the entire day. I have only ever seen him being busy at night just before lights off (at around 11pm). When he is against the glass, I can see that his stomach is fat. There is no obvious damage to his body or anything. I did notice that he likes to feed with my lonely Cory (who doesn't act lonely at all, the crazy thing) which is from the substrate when I drop pellets rather than noming on algae. Is he/she of a different species?
WWM: Possibly.
So you think he is lonely?
WWM: They are social.
Should I buy another one?
WWM: If you can get some from the same batch at the store, sure!
Could it be something else? Water nitrogen param.s are all 0 and PH is 7.4. Temperature is 73F this morning. Not sure about anything else. The other Otos are well fed and "school" together (if you can call two fish a school). The only funny thing is that sometimes one will bend/stretch out his tail slowly all the way to his head, then snapping it straight again. first one way and then another. The only analogy I can think of is how people loosen their necks by slowly tilting their heads side to side. Is this normal behaviour? or should I be looking for parasites and such?
WWM: If he's feeding and has a nice rounded (convex) belly, I wouldn't worry.
Thank you so much in advance. This is my fourth email to you guys and I'm kind of feeling bad about taking up your time...
Thank you for the great work you are all doing.
Re: Otocinclus question - 5/12/2012
Thank you for the prompt response!
WWM: Welcome.
Sadly he's not doing too well today, his previously fat (almost bloated) stomach seems to have deflated profusely in the course of a day. Parasites?
WWM: Possibly. Wild-caught Loricariidae (including Otocinclus spp.) are plagued by both worms and protozoan parasites, and while these rarely cause problems, some species, particularly Otocinclus and Panaque spp., have a reputation for being decidedly hit-and-miss shortly after purchase.
I did realize that for the past two days I have been feeding the tank residents sinking wafers instead of algae wafers.
WWM: Shouldn't have caused this particular issue.
Just when I wanted to pat myself on the back for having a low death rate keeping Otos (1 dead 3 alive so far). It seems that he is blatantly refusing to eat and is dying of starvation.
WWM: Do agree.
It is swimming weakly and sometimes unable to keep its balance. I've taken it out into a smaller quarantine with an airstone. Leaving him some algae wafers and algae covered leaves. But he is either refusing to eat or just to weak to do so.
WWM: Yes.
Also added an IAL (belonging to my Betta), not sure if it will do anything to help
WWM: Me neither.
Its eyes seem hollow and stomach is caving in. His nostrils also seem like a large almost eye sized triangular hole whilst the other two Oto's noses are small holes that protrude slightly outwards.
WWM: Does sound chronic.
This dying Oto is kind of discouraging to me, I have never had a fish die of starvation. and even though I have read that starvation amongst Corydoras have been cured by simply isolating the Cory and giving it food, it seems that Otos are not the caseā€¦
WWM: Correct. As you'll see if you go back over the WWM replies, Otocinclus are not a catfish type with a high success rate in captivity, and I rarely recommend them. Quarantining and deworming, and ideally treating for intestinal parasites (e.g., with Flagyl) are probably very useful.
I also read up on force feeding, but don't believe it can be done with such a miniature fish in its fragile state.
WWM: Quite so. Worth a shot though, and with a hard-bodied fish like an Oto, you might just get away with it. A tiny piece of prawn, pressed into the mouth with a blunt needle or similar could be workable.
I can only come up with a few theories. 1. He is dying of depression without one of the same species.
WWM: Unlikely.
2. He only ate algae wafers and two days without this staple starved him.
WWM: Unlikely.
3. He came with a parasite which caused the bloat then the starvation.
WWM: Agreed.
4. he is an abused Oto and was on its way out when it arrived.
WWM: Agreed.
So this is my 4th Oto, as I always wanted 6 but wanted to work my way up slowly.
WWM: Do buy them the day they arrive, so the pet store has no time to mess them up, and then quarantine them yourself. If you can, proactively medicate.
I don't even know how the first Oto died. he just vanished on the second day of purchase. And try as I might, searching high and low under ornaments and the like, I could not find it. I don't think the resident fish -a Corydoras and an Oto-at the time could have eaten the body. The other suspects were two cherry shrimps and two ghost shrimps. There was no ammonia spike after this death, so I assumed that the plants in the tank simply absorbed the excess. Any recommendations of how I should act now? Should I watch how the other two goes before introducing any more?
WWM: See above.
even though they've been in the tank for a month. Or should I not give up? Is there a recommended "safe period" for quarantining Otocinclus?
WWM: Honestly, no. Quarantining helps, but it's really Russian Roulette with this genus. Warm water slowly kills them (anything above 25 C/77 F) and their natural habitat -- cool, fast-flowing streams with lots of algae -- just isn't often replicated in the community aquarium.
Is there a certain way to condition them to eat vegetables or wafers in case they consume all of the algae in the tank?
WWM: Not really. Green algae is really what they want, so bright light and flat surfaces (like pebbles) are what you need to provide. Algae wafers make an adequate supplement, and some go for finely chopped or small invertebrates. But it's a group of catfish to approach with caution, despite their widespread sale.
I have tried blanched spinach before and never saw them touch it (but I did fish out a horde of baby snails I didn't know I had.) Thank you greatly again in advance for either confirming or correcting my suspicions and answering my questions. Kitty
WWM: Welcome. Best of luck, Neale.
WWM: And thanks for the kind words.

Question about my Oto cat   7/31/11
Hey there,
A while ago I had a 10 gallon tank with 4 Guppies and an Oto Cat.
<A bit small for Guppies.>
The Oto did just fine, was always eating, and very lazy.
<Shouldn't be "lazy" at all. This SCHOOLING species should be buzzing about in a group of five or more specimens, pretty much all the time, flitting from leaf to leaf.>
Now I have a new tank with 4 GloFish and an Oto Cat.
<Again with "an" Otocinclus. They're schooling fish that don't do well singly.>
This is my second Oto for this tank the first died after two days.
<Unfortunately a very common experience. Most aquarists kill their specimens quite quickly, and retailers aren't any better at all.>
When I took it back the pet store they said it was because it was under fed.
<Likely correct. Otocinclus are notoriously difficult to feed. In the wild they consume green algae (not diatoms, and not hair, bush or thread algae either) alongside what is called aufwuchs, tiny invertebrates that live among green algae. In captivity they can be maintained in mature tanks with a combination of green algae, finely minced seafood, and standard algae wafers, but they don't compete well for food and shouldn't be kept alongside greedy fish that feed in the same way, e.g., loaches or catfish.>
So I got another one and put blanched zucchini in the tank, as many sites said they'll like.
<Some specimens will eat softened vegetables, but it's not 100% reliable.>
Problem is he hasn't touched it. I don't want to starve another one.. I have also put in an algae wafer and he hasn't touch that either. He keeps sucking the sides and swimming all over from side to side of the tank like he's looking for something to eat. Any suggestions??
<Will likely not settle down without four or more friends of his own kind.
In a group this species is happier, and therefore more ready to feed.>
Should I just wait to see if he makes it or not?
<If you want, but I'd put money on a swift death.>
Also right now I'm leaving the light on 12 hours to try and grow algae.
<Green algae needs strong lighting to grow. If you have plants that grow so quickly you have to remove a handful of foliage every week or two, you probably have the right amount of light. If your plants basically sit there and throw out the odd leaf every few weeks, then you probably don't have strong lighting and the dominant algae types will be diatoms (the brown scum on the glass) and red algae (hair, brush and thread algae, which aren't red, despite the common name for this group).>
I'm stumped I don't know what else to do.
<I'm surprised you're stumped, because the aquarium literature on Otocinclus spp. is actually quite good. Most any tropical fish book will tell you that these catfish need to be kept in groups, need cool water (22-25 C/72-77 F), and are difficult to feed.>
I attached 2 picture to see if your think he's okay or not. He's slightly blurry because he wouldn't sit still. He's very active. Thank you!!
<Glad to help.>
P.S The pet store got new fish in Thursday and Friday when I brought my dead one back and got the new one, he was the last one left. I'm not sure if they just sold that quick or if there was a reason to why they didn't get more.
<Many pet shops buy Otocinclus because they know [a] they die quickly and [b] people will keep buying new ones to replace any losses. Somehow, there's a rumour that Otocinclus are good algae eaters for small tanks.
That's total and 100% rubbish, but sadly you'll hear it said in some pet shops and written on web sites by people who perhaps don't know any better.
There are some excellent catfish sites, like PlanetCatfish, that will provide very useful information.>
It just seemed weird to me.
<Not weird; typical.>
I checked and there was no dead fish in the tank so I assume they were all in good health. I was thinking of getting another one so he has company, but no other pet stores around here sell them. If this one doesn't work out I'm going to stay away from them for a while as much as I don't want to... I really like these little guys.
<I agree with you that this genus is best avoided by casual aquarists. They can work in largish (20+ gallons?) systems with bright lighting and lots of plants, where there's enough growth of green algae to supplement algae wafers and other such foods. In smaller tanks and less brightly lit tanks they become totally dependent upon the aquarist to feed them, and that is very difficult to do. Not impossible, but difficult, and you do need to ensure two or more small meals per day. Kept singly the poor thing may well be so nervous it'll never feed adequately well. For small tanks Nerite snails are infinitely better algae-eaters, not least of all because they consume diatoms. Hope this helps. Cheers, Neale.>

Re: Question about my Oto cat   7/31/11
Thanks for your help Neale.
<You're welcome.>
So basically I need to get more, which is impossible because the pet store is out,
<Otocinclus spp. aren't rare, and shopping around or online should yield results. Alternatively, ask your retailer to order some in.>
or take him back/wait for him to die and get something else..
<Pretty much.>
do you have any other suggestions other then snails? I always start out with one snail and end up with like 10.
<Nerites don't breed in freshwater; they lay eggs, but the larvae need to drift to the sea and develop in the plankton. This is why I specifically recommend Nerites. One or two per 5 gallons is about right.>
At pet smart they have albino Cory catfish in the tank with the Glofish but it says they get to 3" and I think that's to big for a ten gallon though it says 10+ gallons on the tag.
<Albino Catfish are typically Corydoras paleatus, and while they could be kept in a 10 gallon tank, they wouldn't be my recommendation. Yes, exceptional specimens can exceed 7.5 cm/3 inches, though 5 cm/2 inches is much more typical. Do read the following for more on stocking:
Would it be okay if I moved my Oto out of the tank to feed or would it stress him out more.
<Yes, that would be stressful. Guppies shouldn't compete against him for food, but Corydoras surely would, at least in a tank this small. Nerites and Cherry Shrimps would be the most logical bottom feeders.>
I'm really wanting to keep him around. Thanks again.
<Cheers, Neale.>

algae eating catfish... Oto et al. reading   -- 7/14/10
Hi crew
I've heard about an algae eating catfish referred to as an "Oto". Can you tell me anything about these little guys.
<... read here: http://wetwebmedia.com/FWSubWebIndex/otocinclusart.htm
and the linked files above>
Thank you
<There are better choices for most settings, species mixes... Learn to/use the search tool, indices on WWM. Bob Fenner>

Thank you, Otos  4/6/2009
To whom it may concern,
<Come on Irene>
Thank you for sharing your knowledge and expertise on Otocinclus vittatus.
I have learned much valuable information from your website. I have raised these fish but sadly with no success.
<Not easily kept admittedly... Take a beating through collecting, holding, shipping... and then need a rather narrower range of water quality, consistent... and high DO to do well>
I do not want to give up on the possibility of raising these fish successfully so I am trying to research as much as possible about them as much as possible until I plan to get more. At one time, I had one baby
successfully survive for about a week until it disappeared. I assume it was devoured by one of the
other fish in the tank. The full grown ones did not survive much longer then a month. A couple of times I saw an Otocinclus vittatus move above the water line to suction against dry part of the glass aquarium. I am not
sure if this was normal.
<I do consider this a "normal" part of their (waterfall climbing if you will) behavior>
It seemed strange. One of the fish that did this I believe died as a result of being dried out.
<This is/would be unusual IMO>
Anyhow, thank you for providing thorough information about this interesting fish. I would appreciate any further advice that you may provide me regarding how
to raise them.
Irene Steffen
<To keep gathering information, folks personal experiences as well as scientific. Bob Fenner>

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