Scale-eating Pupfish

About

The scale-eating pupfish (Cyprinodon desquamator) is one of the more remarkable little fish you're likely to encounter in the hobby, not because of its size, it tops out well under two inches, but because of what it eats. This species has evolved to feed on the scales of other fish, a dietary strategy so unusual that researchers have spent considerable effort trying to understand how it developed. Physically, it's built for the job: the jaws are large and positioned near the top of the snout, and the body is noticeably more elongated than its close relatives. Adult males are also easy to spot by their almost entirely black coloration, covering the body and median fins. In the wild, this pupfish is found nowhere on Earth except six small hypersaline lakes on San Salvador Island in the Bahamas, where it shares the water with two other Cyprinodon species. These lakes are shallow and warm, with dense mats of macroalgae along the edges where the fish concentrate. Males hold breeding territories and spawn most actively through the summer months. Given the care level listed as beginner and its compact size, it can work in a small specialized setup, though its scale-eating habit means tankmate selection deserves serious thought.