Tangerine Dwarf Crayfish — CPO (Cambarellus patzcuarensis)

The CPO (Cambarellus patzcuarensis var. Orange) is a genuine dwarf crayfish — maxing out around 1.5–2 inches — selectively bred for a bold orange coloration from a species native to Lake Pátzcuaro in the Michoacán highlands of Mexico. Despite the compact size, it carries full crayfish behavioral complexity: territorial, opportunistic, and constantly active, using those proportionally large claws to investigate every corner of the tank around the clock.

Where full-size crayfish like Procambarus alleni demand large tanks and significant structural planning, the CPO's small footprint lets it work in setups as small as 5–10 gallons, and it's compatible with fish large enough to not become prey. Its tiny mouthparts limit its ability to damage most robust fish, though it will absolutely make an attempt on slow-moving bottom dwellers, soft plant material, and anything that stumbles into reach. Hardy plants attached to hardscape (Anubias, Java fern, Java moss) survive; delicate stem plants don't.

Like all crayfish, it molts periodically to grow — leave the shed exoskeleton in the tank for calcium recovery, and don't disturb a freshly molted animal during the vulnerable soft-shell window.

Scientific name: Cambarellus patzcuarensis var. Orange (CPO)
Origin: Lake Pátzcuaro, Michoacán, Mexico — endemic to a single lake system in the central Mexican highlands
Water parameters: Temp 65–75°F · pH 7.0–8.0 · GH 8–15 (moderately hard; important for proper shell formation)
Tank requirements: 10 gal minimum; provide caves, driftwood, and visual barriers
Diet: Omnivore — sinking pellets, algae wafers, blanched vegetables, small invertebrates
Compatibility: Semi-aggressive with own kind; safe with most community fish; small or slow species at risk
Husbandry note: CPOs are most active in cooler water on the lower end of their range (65–70°F). In warmer tanks (above 75°F) their metabolism runs fast, aggression increases, and lifespan shortens. If they seem hyperactive or aggressive beyond normal, temperature is the first thing to check.