Otocinclus Catfish



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The Otocinclus Catfish is the algae-busting favorite of aquarium hobbyists. Even award-winning planted-aquarium experts like Takashi Amano will employ this tireless algae eater. The diminutive Otocinclus Catfish does a great job keeping aquarium glass and plants free of distracting green. Your aquascape and schooling fish will take center stage when the Otocinclus Catfish turns problem algae into delicious meals using its sucker-type mouth.

The Otocinclus is one of the smallest catfish in the Loricariidae family. Featuring a tan with a black peppered body, the Otocinclus Catfish is an attractive and functional addition to any freshwater aquarium. Originating from fast-moving rivers in South America, the Otocinclus Catfish should be housed in at least a 30-gallon aquarium with high filtration, good water movement, and high aeration. A planted aquarium with rocks and driftwood will provide plenty of hiding spaces to prevent the Otocinclus Catfish from becoming stressed. As a peaceful and very social fish, the Otocinclus Catfish prefers to be kept in small schools.

A planted aquarium with high vegetation and some algae will sustain the Otocinclus. However, if algae are not present, supplement with a vegetable-based flake or wafer food.


{ 7 comments… read them below or add one }

Leeza July 21, 2001 at 12:27 am

This is a cute little fish but it is very difficult to find in the tank. They do on occasion flit by but mostly they stay hidden under a leaf or a log and eat away at algae. The beauty they bring to the tank is an algae-free tank. They do not harm even live plants and about the only thing negative I can say about them is that if they are not fed properly they will sucker to slow moving fish thereby causing wounds and disease. I personally have not seen this behavior in my tank but I have several friends that warned me before I got my otos. I figured danios and tiger barbs probably wouldn’t stand still long enough to allow for that behavior and from all indications I was right. Still I make sure and feed them and do not expect them to exist on algae alone.

MaleRubyBarb February 22, 2002 at 12:27 am

I love these guys. I have 3 ottos in a 30 gallon amazon tank. I recommend more than this. They do a good job, but 3 doesn’t cut it for my tank. They clean it ok, but I think 6 for 30 gallons would be better.

I have 2 ottos in a 55g tank, so they can take care of the algae that may get to my plants. They do a great job here as well. They don’t bother any fish.
They also get to the places my plecoes dont, like my filter ins and outs. Suction cups for my heater.The smaller rocks the plecoes usually swim past.

I keep ottos succesfully in the following conditions.
temp 78
hard water
ph 7.2

also at
temp 73
medium soft water with peat filtration
ph 6.5

seabud March 28, 2002 at 12:26 am

Otos are great little fish. They eat my algae and are cute to watch as they move around looking for food. I had a heater and a bunch of rocks full of brown algae. The 2 Otos I bought had them clean in 3 days. I now add algae pellets twice a week to make sure they have food.

Mine varied greatly in personality, 1 being active day and night, while the other hide during the day and came out only at night for food.

Matt September 17, 2002 at 12:26 am

Oto’s have got my vote of approval! I bought 3 on Friday for my planted 10 gallon tank and by Monday they had my amazons (which had developed an ugly brown algae coating) gorgeously green again. I’ll have to keep an eye on the oto’s to make sure they’re getting enough to eat but for now they’re doing great!

Nathan September 13, 2009 at 9:21 am

Otocinclus catfish are definitely a nice fish to have. They work hard to eat all the algae in the tank. However, don’t expect that they will survive off algae alone. Many people have done this and as a result, have had their Otocinclus starve to death. Unless your tank looks like an algae forest (which is obviously a sign of terrible fishkeeping), you must supplement their diet with algae wafers, or with blanched zucchini, lettuce, or cucumber.

These catfish can be picky about water quality, so good filtration with some water movement is a must. They are not very hardy (especially during the first week of ownership), and you might experience some die-off of them after you purchase them. The reason is linked to how they are caught in the wild, and the lack of appropriate food at the pet store.

I have Otocinclus in all of my planted tanks, and they do a wonderful job of cleaning off algae.

I would definitely recommend Otos to anyone with at least a good knowledge of fishkeeping.

fishboy November 22, 2010 at 6:00 pm

I just love these little guys! I actually have one in my 10 gallon tank. Once I recieve a bigger tank Im probally gonna get a few more! But I think i shouldnt put any more in because then my tank wont grow any more alage! I have a quick question to….

well I have a good sized live plant and a few pieces of decor, but there isnt too much alage growing… Well, if I got another otocinclus would he have enough food to eat? Because I read an article on these little guys and it said they love to school and be in groups!

But other than that I just love the little guys!!!!!!

kilalarae February 6, 2011 at 10:08 pm

I bought 4 oto for my 50 gallon tank and lost 3 within the first week. The one that survived is now longer than my tetra’s and rasbora’s and is pretty fat. I’ve had this one for close to a year now. I purchased 2 more about 2 months ago and they seem to be thriving although I do feed 2 algae wafers every one -two nights. The larger one rarely comes out for the wafer but the smaller ones quickly come out to eat. I think they are really cute little fish and have never had problems with them bothering my other fish. They seem to do well after the first few weeks in the tank but can be difficult to acclimate. The store that I purchase them from always holds them for at least 10 days after arriving so that they can gain weight and recover from any stress.

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