Koi Betta

Looks how to spot one

scales

Koi bettas have the same body shape and fin types as other domestic Betta splendens, but their scales display irregular patches of red, orange, white, black, blue, yellow and metallic shades. This marble-like pattern resembles the colours of koi carp, hence the name. The fins can be long or short (plakat type).12

Personality what they are like

Koi bettas are territorial and aggressive, especially males. They will fight other male bettas to the death and may harass females outside of breeding. They are best kept alone or with very peaceful, non-fin-nipping tankmates in a well-planted aquarium.143

Daily activity how busy a day looks

Low to moderate. Koi bettas are slow swimmers and do not need a large swimming area, but they benefit from gentle water movement and plenty of hiding spots among plants and caves.12

Grooming and care the hands-on bits

Regular water changes (25-50% weekly) are essential to maintain excellent water quality. A filter with gentle flow is recommended. The tank should be heated to 75-84°F (24-29°C). Live plants such as anubias, java fern and floating plants help create a natural environment.123

Home where they are happiest

A minimum tank size of 5 gallons (19 litres) is recommended, though some sources suggest 10 gallons for optimal stability. Water temperature should be 75-84°F (24-29°C), pH 6.0-8.0, with soft water. The tank should have gentle filtration, low water movement, and plenty of plants and hiding places. Koi bettas are tropical fish and must not be kept in unheated bowls.124

Food basics what goes in the bowl

Carnivorous. In the wild they eat insects, larvae and small crustaceans. In captivity they thrive on high-protein betta pellets or flakes, supplemented with frozen or live foods such as bloodworms, brine shrimp and mosquito larvae. Feed small amounts once or twice a day, only as much as they can eat in about 30 seconds.123

Company who they like around

Koi bettas are solitary and territorial. Males must never be housed together as they will fight to the death. Females can sometimes be kept in a sorority with caution, but aggression is still possible. They can be kept with peaceful, non-aggressive fish that do not nip fins, but the betta should be added last to an established tank to reduce territorial behaviour.143

The story where it all began

The koi betta is not a separate species but a colour variety of the domestic Siamese fighting fish (Betta splendens). It was developed through selective breeding for a marble-type pattern that resembles the colours of koi carp. This variety became popular in the aquarium trade for its striking, ever-changing patches of red, orange, white, black and metallic hues. Unlike true koi carp, koi bettas are small, aggressive and kept in heated indoor tanks.12