Rainbow darter

Etheostoma caeruleum

FreshwaterFish

Care at a glance

Temperature: 50–64°F (10–18°C)
pH: 6.5–8.0
Adult size: 2.8 in (7 cm)
Minimum tank: 25 gal (95 L)
Temperament: Peaceful
Social behavior: Solitary
Swim level: Bottom
Difficulty: Medium
Breeding: Hard
Rarity: Very rare
Origin: United States
Family: Percidae

Overview

The rainbow darter is a small, peaceful bottom fish that keeps to itself and needs cold, clean, fast-flowing water to thrive. Give it a gravel and cobble floor with places to perch, and keep only a few together with their own space, since they claim small patches of the bottom. They want live and frozen foods such as bloodworms, blackworms, daphnia and small crustaceans, and rarely settle for flake. Brisk current and cool temperatures are not optional for this coldwater native. A tank of 95 liters or larger with a long footprint and strong flow gives them room along the bottom.

In the wild

Rainbow darters live in the fast, shallow riffles of clear creeks and small rivers across the eastern and central United States, holding position among gravel, rubble and cobble where the current is strongest. The water is cold and highly oxygenated. In the aquarium this means a coarse stony bottom, powerful flow and cool temperatures around 10 to 18 C, well below tropical levels. Keep the pH from about 6.5 to 8 and the oxygen high with vigorous surface movement. Warm, sluggish tanks will not do.

Good to know

The rainbow darter is a member of the perch family Percidae and grows to about 7 cm, with breeding males in brilliant blue-green and orange-red that rank among the most colorful of native fish. It spawns in spring in shallow riffles: the female works her body down into the gravel and lays a few eggs at a time, which the male fertilizes before they are left uncared for. Breeding it at home is difficult because it demands cold, well oxygenated water and a proper riffle to spawn.

Did you know

Breeding male rainbow darters turn brilliant blue-green and orange, giving the fish its name. To spawn, the female wedges the back half of her body down into the streambed gravel and lays just a few eggs at a time for the male to fertilize.