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Otocinclus Catfish

4971 Views 17 Replies 4 Participants Last post by  AltheaGlyndwr
I've read many differing viewpoints on care for these little guys. I recently (just over 2 days ago) aquired an oto and would like to know how people have helped theirs thrive. In my tank I already had 6 Ghost Shrimp, a marimo moss ball, an Endoa plant, a Lucky Bamboo, a filter, heater, a light, and several caves/hidey places with marble pebble terrain. The tank has cycled since becoming established on the 12th of May after I lost my betta and cleaned everything out.

What are special needs I need to be aware of? I already have algae growing in my tank as well as some algae wafers. How often should I actually feed her? (I'm pretty sure its a girl) Also, how long will she take to fully adjust and perk up to be her normal self? At first she went crazy swimming around the tank on the substrate cleaning the algae off of the few rocks I have in there but she has since slowed down and is just kinda chilling in one area of the tank. At one point I actually thought she was dead but then when I moved my hand near her she totally moved. Is there anything that I can do to make her more comfortable while fully adjusting and make sure that she will survive? I've read they're hard to keep unless it's perfect. I also haven't named her yet because I'm scared of losing her (the last time I lost both my betta and the two ADFs within 2 days) and I don't want to do anything wrong.

Also, I know it's not very big, but I'm using a 5 gal cause that's all I have room for until I eventually move and I had been able to upgrade from the terrible .7 I had been using for my poor betta without realizing it was far too small. (When I do finally get the courage and space to get another betta it will only touch that tank if it gets sick as a hosp tank.) I've already learned so much from the community here and I'd really like to make sure I do the best I can with these guys.
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I'm sorry about your betta fish and ADF's. :(
Otos are schooling fish, so it'd be good to get her at least another 2 oto friends. ;) I'm pretty sure the minimum for otos is 10 gallons for a permanent home, 5 should be fine for a while. Take a look at the TFK profile on otos.
Probably gonna sounds dumb but... what is TFK? So I should probably get two more for my 5 gal for right now? They will be ok?
So I have three total now... But one of them looks a bit different from the other two... o_O?
TFK ( is the parent site for; your login will also work there. They have detailed profiles for a lot of tropical fish including oto catfish. You can read it here: Oto Catfish (Otocinclus macrospilus) Profile

From what I've heard about oto catfish, they need a mature tank. The cycle is the just the really tumultuous part of a tank establishing itself. Maturation of a tank happens in the next 3 - 4 months. This is when the biology of the tank is stabilizing; the parameters become pretty set, and the ecological community (algae, bacteria, and other microinverts) become well established.

They are also a schooling fish and do need groups; they also do best in heavily planted tanks. I've also heard they are very very skittish and they poop a LOT. I've considered them for my 29 gal softwater community, but I'm waiting to see how the algae developes. They do need a good supply of algae in the beginning. They are true algae eaters, and all specimens are wild-caught. The tanks they are housed in typically don't have enough algae to sustain them and they arrive in the store half-starved. Once they eat their fill of the algae in your tank, they can be transitioned to algae wafers.
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Thanks~ I didn't realize that there was a parent site >.<;; So there is some algae in my tank, and on my substrate but I don't think there's enough to keep them well fed I don't think... I should feed them the algae wafers as well to make sure they get enough? I also got a vegetable clip. I didn't realize there was a step after cycling the tank... Now I've got to have it become mature x_x lol I hope that these guys will stick with me...
I also will look into getting at least one more plant if not more... Just got to find a place around here that sells like java moss and other such things.
Try to get large-leafed plants like anubias and java fern. Otos really like them. You can also try to entice him with green veggies like zucchini. Those little guys are sensitive little buggers. Best of luck keeping them alive.
Thanks! I think my petsmart has java fern... but don't I have to quarantine it? How long and ca I do that in my .7 hosp tank with dechloinated water?
If the java fern is the "tropical fern" that comes in a tube, you don't have to QT it. Just give it a good rinse off in tap water before you put it in the tank. They might also have anubias in the tubes; my petsmart does. Those are another good choice for your tank. The best way to ID these plants is by the scientific name: anubias (Anubias barteri) and java fern (Microsorum pteropus).
Alright. Thanks. My Petsmart has all their plants in one big flowy area other than their marimo moss which you buy in its on container. So if I get them from there (also I've seen little crawdad looking guys and snails in this flowy water area) how long do I need to keep them seperate or at all?
That is different from the setup my Petsmart has. Since the plants are in contact with water that other fish have most likely been in, I would QT them for about a week. No fish disease can survive that long without a host and will also give you time to pick out any snails that may come with the plant. Be sure to throw away the water the plant comes in because it may be harbouring some diseases. Get some water from your tank, put the plant in that, and set the QT tank by a window. It wouldn't hurt to change the water on your QT tank with water from your main tank once or twice as it will give your plant some more nutrients to stay strong and keep growing.
Alrighty, thank you so much for the advice! I actually lost two of the three of my otos... Not really sure why but I'm still going to get some new plants and plant more in my tank. I will find SOMETHING that will survive :/
Oto cats are very sensitive and really need a well established tank -- one that has been cycled and running for at least 6 months. They also need very clean water, lots of live plants, and hidey holes.

I feed mine cucumbers, zucchini, yellow squash and broccoli. They are so fun to watch flitting around constantly cleaning! :-D

Here's a couple of mine enjoying a piece of squash from my garden:
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I'm sorry you lost some more. Otos are not an easy fish to keep alive. All are wild-caught and usually come to the store in very poor condition. If you can get your tank well-planted and let it age for a while, maybe you can try otos again.
Thanks guys. Here's to trying to help this last little guys survive. Is there anything that I can do for him right now to try and help him survive? He was almost twice as long as the other two (my original died this morning and the midget one last night so now I only have the biggest one left) He appears to have eaten most of the algae wafer I put in there for him... but I can't be sure. And he is constantly moving around.
My suggestion would be to keep his water as clean as possible and keep him well fed. They seem to be either eating or looking for something to eat at all times. If he's eating and is active, I would think that is a good sign.

Mine won't touch algae wafers but love their blanched vegetable slices. You may have to offer vegetables several times before they actually recognize it as food. Although I haven't tried this yet, I have read about people feeding "sheets" of algae that apparently are available at some online fish supply stores.

By the time they reach pet stores, they are in a weakened state because they're half-starved. Also, and I don't know if it's actually true or not, but I've read that when they're caught, cyanide is put into the water to slow them down so that they're easier to catch. So in addition to already starving, they may have also been poisoned.

Good luck with him and I'll be keeping my fingers crossed! :)
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Still alive this morning although not as active. I've been doing 2 gallon water changes like every other day since I got them to try and make sure the water stays clean. I really wish I had a test kit. >.<;;
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