Opae ula

Care at a glance

Overview

The Opae ula is a tiny red brackish shrimp, kept as a colony in a small tank or jar. It is a good first shrimp.

Caring for the Opae ula

Keep Opae ula as a colony rather than a few individuals. They are social, and a group of twenty or more looks and behaves far better than a handful. A jar or small tank of a few liters is enough, at 1 gal (4 L) or more. Give them plenty of surface area for the biofilm and algae they graze.

They want steady conditions far more than a big filtered setup. No filter is strictly required, though a gentle sponge filter and stable warmth do no harm. They need no heater at normal room temperature, within 68 to 82°F (20 to 28°C). A slightly larger open tank with gentle water movement is kinder than a tiny sealed sphere, and it still asks almost nothing of you.

Use low-end brackish water around 1.010 to 1.015 specific gravity, made with marine salt. Hold it stable and alkaline at a pH of 7.8 to 8.5. Top off evaporation with fresh dechlorinated or distilled water to keep the salinity steady. Opae ula tolerate neglect but not sudden swings.

Feed sparingly if at all, since an established tank grows most of their food. They graze the bottom and hardscape constantly and move slowly. They mix only with other brackish-tolerant tank mates and are usually kept alone.

They breed readily in a home tank. Females carry a small clutch and release fully formed miniature shrimp rather than drifting larvae, so a stable colony slowly reproduces on its own.

Good to know

The Opae ula, Halocaridina rubra, is a small atyid shrimp in the family Atyidae. It is extraordinarily long-lived for its size, with individuals reported to live well over a decade and sometimes past twenty years. It is also known as the Hawaiian red shrimp, volcano shrimp or lava shrimp.

In the wild

Opae ula are endemic to anchialine pools on the Hawaiian Islands. These are landlocked brackish pools, fed by underground seawater mixing with fresh groundwater. The habitat is slow, stable and poor in nutrients.

Common questions

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