Mexican blindcat  (Prietella phreatophila)

Classified as Endangered (EN) on the IUCN Red List 2007 (1).

This small, rare fish, which possesses no eyes, inhabits underground waters in Mexico. The Mexican blindcat has a pinkish-white, smooth, scaleless body with four pairs of long, whisker-like barbels around the mouth (2) (3) (4). The adipose fin on the back is joined to the caudal, or tail, fin (2). Well-developed pores on the head (2), linked by canals, form the lateral-line, a sense organ used to detect movement and vibration in the surrounding water.

The Mexican blindcat occurs in the state of Coahuila, Mexico (2).

Inhabits subterranean freshwater in cave environments (5)

Like many organisms that inhabit caves the Mexican blindcat possesses no eyes, which is compensated by the development of other senses (5). Studies have shown that the Mexican blindcat has acute hearing and can rapidly perceive the odour or taste of non-moving food, such as mosquito larvae (6). Aggressive encounters between Mexican blindcats have been observed, during which they bite at one another and then lock jaws, often remaining in mouth to mouth contact for many hours. All of the aggressive individuals appeared to be males (6); however, the reason behind this hostile behaviour is not yet fully understood. Mexican blindcats have also been seen resting motionless on the substrate, or drifting with currents. This behaviour would seem to leave this small fish extremely vulnerable to predation, and thus may reflect the lack of predators in their natural habitat (6).

The Mexican blindcat is considered by the World Conservation Union (IUCN) to be Endangered, due to its restricted range and an inferred population decline (1). The region in Mexico the blindcat inhabits is facing rapid population growth, resulting in increased pressure on groundwater resources. Interviews with local people indicate that the water tables have declined in recent decades, which reduces the amount of available habitat for the Mexican blindcat. Growing human populations also results in increased pollution, which could contaminate the groundwater (6), further threatening the existence of this fish.

Despite the threats it faces, the Mexican blindcat may inhabit underground waters that are undiscovered or inaccessible to humans, and therefore the total number of individuals could potentially be large (6). Further research to determine the population size and conservation status of the Mexican blindcat is required to inform future conservation actions to protect this peculiar species.

View information on this species at the UNEP World Conservation Monitoring Centre.

For further information on the Mexican blindcat and other fish in Mexico see:

• Miller, R.R., Minckley, W.L. and Norris, S.M. (2004) Freshwater Fishes of Mexico. The University of Chicago Press, Chicago.