PISSKER, in ichthyology, is a fish of the mussela kind, commonly called the fossile mussela, or fossile fish. They are generally found as long as an ordinary man's hand is broad, and as thick as one's finger; but they sometimes grow much longer: the back is of grey with a number of spots and transverse streaks, partly black and partly blue; the belly is yellow, and spotted with red, white, and black; the white are the larger, the others look as if they were made with the point of a needle; and there is on each of the sides a longitudinal black and white line. There are some fleshy excrescences at the mouth, which are expanded in swimming; and when out of the water, they are contracted. These fishes run into caverns of the earth, in the sides of rivers, in marshy places, and penetrate a great way, and are often dug up at a distance from waters. Often, when the waters of brooks and rivers swell beyond their banks, and again cover them, they make their way out of the earth into the water; and when it dries, they are often left in vast numbers upon the ground, and become a prey to swine. It is thought to be much of the same kind with the figum fish; and it is indeed possible that the pacilia of Schonefeldt is the same.