Marine betta (Calloplesiops altivelis) care guide

Group
Marine fish
Other names
Comet, Comet grouper
Family
Plesiopidae (longfins and roundheads)
Origin
Indo-Pacific tropical reefs, usually 3–50 m; adults live around caves and crevices on drop-offs.
Water
saltwater
Maximum size
15 cm
Temperature
24–27°C
pH
8.1–8.4
Hardness
Salinity SG 1.023–1.026
Minimum tank
300 litres
Care level
intermediate
Temperament
peaceful
Reef safe
yes

Care

Tank and decor: plenty of caves and overhangs and fairly subdued lighting. It can be kept in a reef with suitable tankmates. The tank size given is an estimate based on its adult size and habits. Water: the sources give no species-specific figures, so the values here are general marine aquarium guidance: 24–27 °C, pH 8.1–8.4 and specific gravity 1.023–1.026. Keep nitrate low and the water well oxygenated. Behaviour: nocturnal and shy, hiding under ledges by day. It approaches prey sideways. When threatened it pushes its head into a hole and shows its tail; the eye-spot on the dorsal fin makes the rear of the fish look like a moray eel’s head. Identification: dark brown to black covered in small white spots, with very large fins and a false eye-spot near the back of the dorsal fin. The list gives 15 cm; the article gives up to 20 cm. Trade: a popular aquarium fish. The article gives no IUCN or CITES status. Sources: Wikipedia, List of marine aquarium fish species (en.wikipedia.org/wiki/Listofmarineaquariumfishspecies); Wikipedia (en.wikipedia.org/wiki/Calloplesiopsaltivelis). Checked October 2026.

Diet

Eats crustaceans and small fish. It often accepts only live food at first and stalks its prey slowly, so start with live shrimps and wean it on to frozen mysis and chopped prawn. Make sure it gets food before faster tankmates do.

Breeding

Has been bred in captivity; the sources give no further details.

Compatibility and tank mates

Peaceful towards fish it cannot swallow, but it will eat small shrimps and very small fish. Because it is a slow feeder it can starve alongside fast predators such as lionfish and groupers. Leaves corals alone.

Last updated 8 October 2026. Community-edited care guide on Aquatic-Auctions.

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