TankBud

Marine betta

Calloplesiops altivelis

Also known as Comet, Marine Betta Comet, Comet Grouper

SaltwaterFish

Marine betta (Calloplesiops altivelis)
Diego Delso · CC BY-SA 4.0

Care at a glance

Temperature
73–81°F
23–27°C
pH
8.1–8.4
Adult size
6.3 in
16 cm
Minimum tank
55 gal
210 L
Temperament
Peaceful
Social behavior
Solitary
Tankmates
With caution
Swim level
Middle
Diet
Carnivore
Difficulty
Medium
Breeding
Medium
Rarity
Common
Reef safe
Reef safe with caution
Family
Plesiopidae
Origin
Indo-Pacific, from the Red Sea and East Africa across to the Line Islands and Tonga

Overview

The marine betta is a secretive reef predator that drifts slowly with its fan-like fins spread wide. Once settled and eating, it is hardy and long-lived, and it suits a keeper with a little experience.

Did you know

The marine betta's tail-end eyespot lets it pass for a moray eel. When it hides head-first in a crevice, a would-be predator sees what looks like the toothy face of a moray staring back out.

Caring for the marine betta

Keep a marine betta in a mature tank of at least 55 gal (210 L) with generous live rock. It needs dark caves to retreat into and dim or low-flow areas where it feels secure. Hold the water at 73 to 81°F (23 to 27°C) and a pH of 8.1 to 8.4.

It is shy and slow to acclimate, and boisterous tank mates can outcompete it for food or bully it. Feed meaty foods such as mysis, chopped seafood and clam.

The marine betta is peaceful, and a calm tank suits it best. It ignores corals, anemones and sessile invertebrates completely, but it will eat small fish, ornamental shrimp and other bite-sized crustaceans. That makes it reef safe only with caution.

Keep one per tank, as they can be aggressive toward their own kind. Breeding them is moderately hard.

Good to know

Calloplesiops altivelis belongs to the family Plesiopidae. Its dark body is dotted with white spots, and its rear dorsal fin carries a large false eyespot, or ocellus. Together they mimic a whitemouth moray eel (Gymnothorax meleagris), and this Batesian mimicry deters predators.

In the wild

The marine betta lives across the Indo-Pacific, from the Red Sea and East Africa to the Line Islands and Tonga. It is largely nocturnal, hiding in reef caves, ledges and overhangs by day and coming out to hunt at dusk and night.

Common questions

What size tank does a marine betta need?

A marine betta needs at least 55 gal (210 L). It spends most of its time in the middle.

What temperature and pH does a marine betta need?

A marine betta is comfortable at 73–81°F (23–27°C) with a pH of 8.1–8.4.

What does a marine betta eat?

A marine betta eats meaty foods such as mysis, chopped seafood and clam. It will also eat small fish, ornamental shrimp and other bite-sized crustaceans in the tank.

How big does a marine betta get?

An adult marine betta reaches about 6.3 in (16 cm).

Related species