ANIMAL: Blind Cave Tetra/Blind Cave Fish Astyanax jordani Type of Animal: Characin Habitat: Caverns, caves, small streams, flowing rivers created from mountain runoff, running waters of lakes/rivers, live in neutral waters w/ temps of 68-77 F, not found outside of cave/cavern associated areas Location(s): NE Mexico Appearance: Small fish w/ cream to light pink coloration, often have silver linings, some populations eyeless Food/Diet: Worms, snails, small crustaceans, small fish, insects, algae, plant matter Status in Wild: Threatened Conservation: Breeding in aquariums, zoos, & aquaculture. Monitoring of wild populations. Lifestyle: Schools of 5-100 fish Additional Info: Called: Male Female Young: Fry Group: School Weight: Male: 0.08-0.09 oz Female: 0.1-0.2 oz Gestation: 1 day Life Span: 4-10 years Body Length: Male: 3.5 in Female: 4 in Tail Length: 0.3 in, same for both sexes Main predators are larger fish (including larger cavefish). These fish compensate for lack of sight by having more sensitive lateral line system detecting vibrations/pressure changes in water. Eye sockets covered w/ scales appearing as dark spots. They use their more sensitive lateral line system to find food & avoid bumping into things. Courtship involves breeding pair making exaggerated mouth/gill movements, then swimming side-by-side. Fertilized eggs sink to bottom sticking to rocks. They have normally developing eyes when growing in egg but eventually the eyes will degenerate. These fish can either hatch totally blind (typically only happens in isolated caves/caverns) or hatch w/ functional eyes which later cloud over/shrink. Also called Blind Cave Characin, Mexican Blind Cave Fish, Mexican Blind Cave Tetra, & Blind Tetra. Sometimes hybridize w/ closely related Mexican Tetra. Most fish in aquarium trade derived from stock collected in Cueva Chica Cave in S part of Sierra Del Abra cave system in Mexican state of San Luis Potosi in 1936. These fish sent to aquarium company in Texas, then being distributed on larger scale. Since then, they’ve become popular due to ability to survive w/o sight & in complete darkness. Threatened due to aquarium trade, water pollution, specialized habitat preference, & habitat loss/alteration. Fun Fact(s): Since they have extremely poor eyesight, they utilize orientation, smell, & other senses. In isolated caves/caverns, these fish totally blind but in caves connected w/ more light, they have almost functional eyes (eyesight poor either way). These fish have been used in evolutionary studies due to their uniqueness. These fish 1st discovered in 1930s.
