Calico Crayfish Orconectes

Orconectes immunis is a widespread plains and prairie crayfish of central North America, found across a vast range from Kansas and Nebraska northward into Canada. It is one of the most cold-tolerant freshwater crayfish in the hobby and can thrive in unheated aquaria year-round in temperate climates. Its natural mottled calico patterning of brown, cream, and olive-green is subtle but attractive under good lighting.

This species is highly adaptable, surviving in standing water, slow streams, and even temporary pools — a testament to its hardiness. In aquaria it is an active burrower and will rearrange substrate constantly. Its cold tolerance makes it an excellent candidate for unheated display tanks in temperate climates.

Because of its wide native range and adaptability, O. immunis is considered by some authorities to be invasive outside its core range. Keepers should check local regulations before acquiring this species and never release it into natural waterways.

Water: 10–24°C, pH 7.0–8.0, GH 5–20, KH 2–15; very cold-tolerant; unheated tanks suitable. Tank: minimum 80 L, sandy substrate for burrowing, caves, tight lid; avoid plants. Feeding: omnivore — sinking pellets, leaf litter, blanched vegetables, occasional protein. Breeding: breeds in cooler months; female broods eggs; juveniles independent at hatching. Compatibility: territorial — keep alone; compatible with robust cold-water upper-column fish.