In the family Aphredoderidæ but one species is known, Aphredoderus sayanus, the pirate-perch. It reaches a length of five inches and lives in sluggish lowland streams with muddy bottom from New Jersey and Minnesota to Louisiana. It is dull green in color and feeds on insects and worms. It has no economic value, although extremely interesting in its anatomy and relationship.
Whether the Asineopidæ, fresh-water fishes of the American Eocene, and the Erismatopteridæ, of the same deposits (see page [235]) are related to Aphredoderus or to Percopsis is still uncertain.
Fig. 230.—Skull of the Rock Bass, Ambloplites rupestris.
The Pigmy Sunfishes: Elassomidæ.—One of the most primitive groups is that of Elassomidæ, or pigmy sunfishes. These are very small fishes, less than two inches long, living in the swamps of the South, resembling the sunfishes, but with the number of dorsal spines reduced to from three to five. Elassoma zonatum occurs from southern Illinois to Louisiana. Elassoma evergladei abounds in the Everglades of Florida. In both the body is oblong and compressed, the color is dull green crossed by black bars or blotches.
The Sunfishes: Centrarchidæ.—The large family of Centrarchidæ, or sunfishes, is especially characteristic of the rivers of the eastern United States, where the various species are inordinately abundant. The body is relatively short and deep, and the axis passes through the middle so that the back has much the same outline as the belly. The pseudobranchiæ are imperfect, as in many fresh-water fishes, and the head is feebly armed, the bones being usually without spines or serratures. The colors are often brilliant, the sexes alike, and all are carnivorous, voracious, and gamy, being excellent as food. The origin of the group is probably Asiatic, the fresh-water serranoid of Japan, Bryttosus, resembling in many ways an American sunfish, and the genus Kuhlia of the Pacific showing many homologies with the black bass, Micropterus.
Fig. 231.—Crappie, Pomoxis annularis Rafinesque. Ohio River.
Fig. 232.—Crappie, Pomoxis annularis (Raf.). (From life by Dr. R. W. Shufeldt.)