Collision with and avoidance of obstacles by blind cave fish Anoptichthys jordani (Characidae).

Blind Mexican cave fish (Anoptichthys jordani) were released into unknown surroundings and their swimming tracks were recorded. During the first 24 h in a new tank, i.e., in unfamiliar environments, the average swimming velocity of the fish was higher than during the remaining time in the tank. Collision with obstacles was recorded by an electrical contact detection method. Single frame analysis of video-recordings revealed that collision can be correlated with tail movements when the fish is close to an obstacle, whereas avoidance correlates with gliding during approach to an obstacle. These behavior patterns are discussed in the context of the flow field hypothesis and inhibition of the lateral line organ during movement.