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EveryFish
Mesonauta festivus

Flag cichlid

A South American cichlid from river basins in Brazil and Bolivia.

Photo: Citron, CC BY-SA 3.0, via Wikimedia Commons

The flag cichlid is a freshwater fish native to major river systems in South America. It grows to about 12 cm and is kept by hobbyists in home aquariums. Taxonomic updates have clarified its distinction from similar relatives in the same genus.

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  • Reaches a standard length of 12.1 cm
  • Native to Paraná and Paraguay river basins
  • Found in Brazil, Peru, Paraguay and Bolivia
  • Often confused with M. guyanae in aquariums

What it is

The flag cichlid is a member of the cichlid family found in South America. It has a compact body shape typical of the group and reaches a standard length of roughly 12 centimetres. This species was once thought to be the only valid member of its genus, but later studies identified several distinct relatives. It is recognised by its specific range and physical traits that separate it from similar looking fish.

Where it lives

This fish inhabits several major river basins across the continent. Its distribution includes the Paraná, Paraguay, Madre de Dios, Guaporé, Mamoré, Jamari and Tapajós systems. These waters flow through Brazil, Peru, Paraguay and Bolivia. The species occupies freshwater environments within these extensive drainage networks, distinguishing its habitat from northern relatives that live in different catchment areas.

Flag cichlid
A drawing made by EveryFish from what this page says. It is a diagram, not a picture of the real fish.

Fish and people

Aquarium enthusiasts keep this cichlid in home tanks. For many years, hobbyists labelled various specimens as this species due to limited taxonomic clarity. Now that other members of the genus are better defined, true flag cichlids appear less frequently in the trade than their relatives. Fish keepers may encounter similar looking species such as M. guyanae or M. insignis instead of this particular fish.

Flag cichlid, Mesonauta festivus (Heckel, 1840), Natural History Museum University of Pisa
Flag cichlid, Mesonauta festivus (Heckel, 1840), Natural History Museum University of Pisa. Photo: Mattia Nocciola, CC BY-SA 4.0, via Wikimedia Commons

Questions people ask about Flag cichlid

Where does the flag cichlid live?

It is native to freshwater river basins in South America, including the Paraná, Paraguay, Madre de Dios, Guaporé, Mamoré, Jamari and Tapajós systems across Brazil, Peru, Paraguay and Bolivia.

How big does this fish grow?

The flag cichlid reaches a maximum standard length of approximately 12.1 centimetres, which is just under five inches. This size makes it suitable for medium sized community aquariums.

Is this the same as the festive cichlid in shops?

Not always. Many aquarium specimens were historically labelled as this species, but taxonomic reviews show that relatives like M. guyanae and M. insignis are more common in the trade today.

Good reading and sources

Where this page comes from

The facts on this page come from the Wikipedia article "Mesonauta festivus", written by its contributors and used under the CC BY-SA 4.0 licence, and from its Wikidata record (CC0). EveryFish rewrote the text in its own words, with AI assistance, and compares every page with the article to make sure no passage is copied. It may be reused under the same CC BY-SA 4.0 licence with a link back.

It may contain mistakes, and figures change over time. Nothing here is investment or buying advice. If something is wrong, tell us. Last refreshed 2026-11-15.

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Photo credits on this page

The small pictures above come from Wikimedia Commons under free licences. Some are cropped to fit.

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