Care Guide For Otocinclus

Care Guide For Otocinclus

  • Author Initiate
  • Creation date
I love Ottos so I wanted to make this thread so people can look after them properly and have success with them.

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. They can live in groups of hundreds.

Otocinclus are often caught from the wild, sometimes chemicals (I think cyanide or something) 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 arriving in bad condition already 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 is a sure sign the fish is starved and will most 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, ottos will always be healthier when their food source is made of mainly algae.

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 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 while 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 A LOT OF ALGAE. This is so so so important, many ottos wont eat algae wafers or other vegetables when first bought. Do not buy ottos unless you have algae in your aquarium, ottos go through a lot of it because they 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 and contributes to their diet. A combination of hiding places are important as they can stress easily, plant cover is recommended.

pH - 6.2 - 8.0 ( Closer to 7 is recommended but consistency is better than accuracy. Don't chase the perfect pH. )

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 it old and established.

Tank Size - 10 gallon Minimum (Depending on the size of your group size you'll need to have a big enough tank to accomodate their algae requirements)

Size - 2" Max ( Less common Ottos can be larger)

Lifespan - 3 - 5 Years


Otos seem to take a while to realise that foods such as algae wafers and vegetables are food. So leave the foods in their consistently until they realise that it is.

Their diet mainly consists of algae otos will sometimes 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.

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, this will give them something to chew on and fill their stomachs.


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 BELLYS! If their belly's are sunken then they are not receiving enough food. Please please check regularly for rounded belly's not just one ottos but all your ottos.

Otos will interact with some other fish a good is example is them sitting by corydoras.

Tank Mates

Ottos are extremely peaceful some aquarists even keep them with baby shrimp. Semi-aggressive fish should be carefully chosen. I keep mine with a dwarf gourami he doesn't go after them but touches his nose on them when he becomes curious, they quickly dart away. Corydoras go perfectly with Ottos they have even been observed to sit next cories. With no defence system apart from a semi-hard set of scales ottos require tank mates that will not bother them.

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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