Fish o' the Day - pirate perch

Here's a nice one. The pirate perch, Aphrododerus sayanus, is deep-bodied, with a perch-like appearance as suggested by the common name. However, the single arching dorsal fin gives them away. In fact, this is the only living member of its family, Aphrododeridae. Adults are typically 4-5" long, and are usually a fairly uniform brown. They're found in slow-moving streams and ponds in most of the major Eastern drainages - we get them in backwater areas off of a number of the streams we work. Pirate perch are actually a rather unassuming-looking fish, until you look more closely. The unique thing about them is the placement of the urogenital opening. As pirate perch mature, the cloaca moves progressively toward the anterior end of the fish - in mature individuals, it's in the throat region. Of course, when we see something like that we want to know why. For a while, it was assumed that the fish must be mouth- or gill-brooders, but no evidence was found.

A 2004 paper in Copeia seems to have provided the answer. Pirate perch spawn in tangled underwater root masses. The females push their head into the tangle, and release the eggs through their forward-placed urogenital opening. Males then follow suit, and fertilize the eggs.

Something we'll play with this summer in the fish class.