Rainbow shark

Epalzeorhynchos frenatum

FreshwaterFish

Care at a glance

Temperature: 68–79°F (20–26°C)
pH: 6.5–7.5
Adult size: 5.9 in (15 cm)
Minimum tank: 32 gal (120 L)
Temperament: Mostly peaceful
Social behavior: Solitary
Swim level: Bottom
Difficulty: Medium
Breeding: No record
Rarity: Common
Origin: Thailand, Laos, Cambodia
Family: Cyprinidae

Overview

Best kept as a single specimen, since it is solitary and territorial toward its own kind and similar-looking fish. It lives on the bottom and needs a tank of at least 120 liters with clear sight lines broken up by decor. Keep it in the low to mid 20s C with a pH of 6.5 to 7.5. It eats algae, sinking pellets, and frozen foods. House it with active mid and upper level fish it can largely ignore, and avoid other bottom dwellers it will harass.

In the wild

Rainbow sharks come from rivers and streams in Thailand, Laos, and Cambodia, where they graze biofilm and algae off the bottom and patrol a patch of riverbed. Give them a roomy tank with caves, rocks, and wood to claim as territory, and a sand or smooth gravel bottom. Hiding spots matter, since this fish wants a base to defend.

Good to know

This is a member of the Cyprinidae, the carp and minnow family, not a true shark. It is named for its tall, sail-like dorsal fin and grows to about 15 cm. Breeding in home aquariums is rarely recorded, and most fish in the trade are commercially raised with hormones. The wild population has declined, though aquarium stock is plentiful.

Did you know

Rainbow sharks get more aggressive as they mature, and they are especially rough on anything that resembles them, including red-tailed sharks and other rainbow sharks. That is why one per tank is the standard advice.