Catfish are often described as “algae eaters”. Although many species scrape between the algae and ingest algae, not all of them are algae eaters. Some also need meaty food or need to be able to scrape their food off the wood and need the wood fibers for their digestion.

L-number fish

A large part of the known species that we call catfish have a so-called L number. The L stands for Loricariidae, a family of fish species from South America. Many new species were discovered, not all of which have been immediately described. With the L-numbers they got a temporary number. After they have been given an official name, the L number officially expires, in practice it often remains for a long time.

Algae in Aquarium

Not all catfish actually eat algae. Below you will find three types that are often used to control algae in the aquarium.


Without discussion at number 1 is the common Ancistrus. In the store they are also called bristlenose pleco. The males develop a kind of bristle on their noses to impress the females.

They are usually calm fish that clean the glass and free it from algae. Black beard algae is also eaten by this algae eater. Unfortunately, they leave filamentous algae alone.

Ancistrus sp. removes spot algae from glass
Farlowella vittata 1

Siamese Algeneter – Crossocheilus oblongus

The Siamese Algae Eater is an excellent species to remove not only beard algae and pointed algae, but also thread algae. They just grow a bit larger than the Ancistrus. They can reach a maximum total length of about 25 centimeters! In the long term, they are therefore only suitable for the somewhat larger aquariums.

When young, they live in groups. As they get older and bigger, they become a bit intolerant of conspecifics. It is therefore better to keep them solitary at a later age.

Crossocheilus oblongus – Siamese Algae-Eater
Farlowella vittata 2

Otocinclus affinis – Otocinclus vittatus

An algae eater for the smaller aquariums (Nano aquariums) is the Otocinclus. In the shop you often find Otocinclus affinis or Otocinclus vittatus….usually one of these names, but people often don’t know which species it actually is.

It is a somewhat delicate fish. Only place them in a matured aquarium where they can find plenty of food. Don’t combine them with fish that are too busy!

This algae eater loves brown algae. They are less likely to eat black beard algae or point algae. You can also use shrimp for that type of algae in a Nano aquarium.


John de Lange

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