Care Guide For Otocinclus

Care Guide For Otocinclus

  • Author Initiate
  • Creation date
A Few Important Pointers
  • Ottos are not recommended for beginners
  • Ottos need large amounts of algae as this is their main food source
  • Water parameters need to be perfect for these fish as they are sensitive to new environments.
  • Ottos need to live in groups of six or more. (10 - 15 is recommended)
  • Ottos are only sensitive during their initial period of being added to the tank (Up to 2 months) after this they become extreme hardy.
  • It is not uncommon to lose half the ottos you buy.

Origin and Collecting of Otocinclus

Originating from South America the Otocinclus feeds on algae and biofilm within shallower areas of the river.

Otocinclus are often caught from the wild, cyanide is added to the river upstream to sedate the fish, making them easier to catch. They are then shipped to countries around the world. They are starved during this shipping period and sometimes at the wholesalers before they reach your Local Fish Store.

They are already arriving in bad condition at your LFS often starving, it's common for your LFS to lose half to ottos they buy if they haven't bought from a reputable wholesaler. It is USUALLY not their fault for your ottos death.

Buying Ottos

Look for round, 'fat' stomachs, the bigger the stomach the better. Sunken stomachs are bad and are a sure sign the fish is starved and could likely die. Only buy if their stomachs look full and obviously if the fish is generally healthy. It is also important to check if there is algae in the tank although not essential if the tank is fed algae wafers/algae-based food.

BUY OTTOS IN GROUPS OF 6 OR MORE! The more the better, ottos are found in the wild in groups of hundreds, solitary ottos or small groups will not display the best behaviour and may become constantly stressed.

Acclimating and Quarantining Ottos

Acclimating is very important with Otocinclus as they are very sensitive to new environments. From experience and from what other people have said drip acclimation is recommended. Some aquarists say that when they used the plop and drop method they lost the majority or, all of their ottos. Whereas when they drip acclimated they have had no loses or very few.

Quarantine is important with otocinclus just as it is with any other fish to prevent disease affecting other fish in your aquarium. BOTH THE QUARANTINE AND THEIR TO-BE HOME NEED ALGAE. This is so so so important, many ottos won't eat algae wafers or other vegetables when first bought. Do not buy ottos unless you have algae in your aquarium, ottos are constantly grazing throughout the day and it is their main food source.

A four week quarantine period is recommended as with any other fish before being added to your aquarium. ALGAE IS MORE IMPORTANT THAN QUARANTINE! If there is algae in your main tank and not in your quarantine then they should always be added to the main tank.

Aquarium Setup

A sandy or smooth surfaced gravel is recommended, although the majority of the ottos time is spent grazing on algae. They do spend some time on the bottom of your tank. Hiding places are also important especially when keeping them with semi-aggressive fish such as dwarf cichlids. Live plants are also important and the ottos will eat algae off of them which many other larger aufwuchs grazers cannot offer. Wood is also especially important as the fish will graze on it and also attempt to camouflage on the driftwood if feeling threatened. Provide a shaded area, with plants, for the otocinculus as they often like to escape the light.

pH - 6.2 - 8.0 ( Closer to 7 is recommended but consistency is better than accuracy. Don't chase the perfect pH. ) With all fish, they can usually adapt to your pH level as long as it isn't at an extreme.

Temperature - 72F - 80F ( Although they seem to like cooler water. ) Temperature fluctuations can be fatal to otos.

PARAMETERS MUST BE PERFECT! Ottos are sensitive to ammonia and nitrite, these fish should be added only once your aquarium is old and established. Ottos are not a beginner fish either, if you haven't been in the hobby for long then failure with these fish will occur. At the same time, an unestablished tank will lead to failure.

Tank Size - 10g Minimum (Depending on the size of your group size you'll need to have a big enough tank to accommodate their algae requirements) I personally would recommend at least a 20g for beginners at a minimum.

Size - 2" Max (There are various strains of the fish, so size will vary between subspecies)

Lifespan - 3 - 5 Years


Many otocinculus will not recognise algae wafers or greens such as cucumber as something that is edible when first purchased, the fish will need to be introduced to these foods over time until they realise it is edible.

Their diet mainly consists of algae. Otos will also feed on the biofilm found only within established older tanks. Their diet may be supplemented with cucumber and zucchini. Most hobbyists attach the vegetables to a clip and stick it to the glass with magnets. The vegetables should not be left in the tank for longer than 24hrs as the vegetables can start decaying, therefore, releasing ammonia.

OTOCINCLUS ARE OMNIVORES- LIKE ALL FISH PROTEIN MUST BE PROVIDED PERIODICALLY. This can be done in the form of shrimp wafers which are fed to corydoras.

Some people start 'algae farms' where a container is filled with water, left outside and for example, glass bottles are left inside to grow algae, when the glass bottles have enough algae they can be left in the tank for the ottos to chow down on.

It is also important to have driftwood in the aquarium especially when first introducing them. Like plecos, otos will graze on driftwood.


Ottos constantly dart around the tank this is not a sign of stress. They may also bump into other ottos when grazing on surfaces this is not a sign of aggression.

OTTOS SHOULD ALWAYS HAVE ROUNDED BELLIES! If their bellies are sunken then they are not receiving enough food. Please please check regularly for the rounded belly's, not on just one otto but all your ottos.

Tank Mates

Ottos are extremely peaceful, they can be kept with shrimp and will not ruin plants. They have the ability to reach spaces where other larger fish cannot. Along with this, they are highly adaptive to their environment in the sense that they may become nocturnal when living with somewhat aggressive fish to avoid them. They can be kept with all the tetras, guppies, etc. They have been kept with Dwarf Gourami, Angelfish, Discus, Dwarf Cichlids. They can handle a majority of community-style tank mates.

Resources -


If you have any corrections, suggestions or need help please comment so I can make the edit or help you.

- Initiate
First release
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  • nimahs
  • 5.00 star(s)
I can tell you really care about your Ottos. Very helpful, especially the part about making an algae farm. My future ottos lives will be much better bc of you :)
Definitely covers everything a beginner would need to learn about Otos. Came here because my Otos lately have been expressing more active behavior. Before they were less active and hid lots. Now they usually can be seen cruising the glass. Didn't get what I came for, but found a quality article.
This was a great write up. I have become a belly watcher too.
This article was very thorough and obviously well researched. I learned a lot of new stuff here that was useful right off the bat.
Much obliged OP
Very helpful. I have a 60 gallon filled with algae so they are very happy ottos. You have made me a belly watcher.
I found that this resource gave a good general information on their care and needs. Many people tend to overlook them and recommend them without taking any of the things mentioned to mind.
Thanks really appreciate your review!
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