Mexican Blind Cave Tetra

Astyanax mexicanus cave morph is one of the most scientifically fascinating fish in the hobby, having evolved complete eye loss and loss of pigmentation through millions of years of life in the lightless caves of Tamaulipas and San Luis Potosí, Mexico. Despite being sightless, it navigates with extraordinary precision using a highly developed lateral line system to detect water pressure changes. In the aquarium it is surprisingly robust, accepting a wide range of conditions and foods. It can coexist with surface-form conspecifics but may be kept alone or in small groups. An unmissable species for educators, biologists, and curious hobbyists.

Water: pH 7.0–8.0, temperature 18–25 °C; moderately hard to hard. Tolerates cooler temperatures. Tank: 80 L minimum; avoid sharp decor that could injure eyeless fish. Smooth rocks and soft plants preferred. Feeding: Omnivore; accepts all foods readily; feeds by smell and pressure detection. Feed consistently at same spot. Breeding: Egg-scatterer; spawns readily. Surface-form and cave-form can hybridize. Compatibility: Peaceful but best kept with similarly sized robust fish. May nip fins occasionally.