Fam. 1. Characinidae.—Mouth non-protractile, usually bordered by the praemaxillaries and the maxillaries, rarely by the praemaxillaries only; jaws usually toothed. Parietal bones united in a sagittal suture or separated by a fontanelle; opercular bones well developed; symplectic present. Pharyngeal bones normal, with small teeth. Ribs mostly sessile; no parapophyses in the thoracic region; epipleurals and epineurals, mostly free floating. Pectoral fins inserted very low down, folding like the ventrals. Body covered with scales. An adipose dorsal fin often present.
This is a very generalised type, although perhaps not directly derived from the bony Ganoids, as believed by Sagemehl. The species number about 500, and are confined to the freshwaters of Africa and Central and South America. The classification of the family is still in an unsatisfactory state, but the division into the following groups (hardly deserving the rank of sub-families), although quite provisional, appears preferable to the highly artificial arrangement hitherto adopted:—
I. No adipose fin.
A. Erythrininae.—Carnivorous; teeth strong; maxillary large; gill-openings wide; scales cycloid. American: Macrodon, Erythrinus, Lebiasina, Pyrrhulina, Corynopoma.
II. Adipose fin usually present.
B. Hydrocyoninae.—Entirely or partially carnivorous; teeth strong; maxillary well developed; scales cycloid; lateral line usually nearer ventral than dorsal outline (sometimes only on the tail). African: Sarcodaces, Hydrocyon, Bryconaethiops, Alestes, Micralestes, Petersius. American: Acestrorhynchus, Boulengerella, Acestrorhamphus, Crenuchus, Chalceus, Brycon, Bryconops, Bryconodon, Creagrutus, Chalcinus, Brachychalcinus, Pseudocorynopoma, Stichonodon, Gastropelecus, Tetragonopterus, Scissor, Chirodon, Piabucina, Iguanodectes, Aphiocharax, Salminus, Oligosarcus, Agoniates, Paragoniates, Leptagoniates, Anacyrtus.
C. Serrasalmoninae.—Carnivorous; teeth strong; belly serrated; scales cycloid. American: Serrasalmo, Myletes, Myleus, Metynnis, Catoprion.
D. Ichthyoborinae.—Carnivorous; teeth strong; maxillary very small; upper jaw movable; scales ciliated. African: Eugnathichthys, Paraphago, Mesoborus, Phago, Ichthyoborus, Neoborus.
E. Xiphostominae.—Carnivorous; teeth very small; maxillary rather small; scales ciliated. American: Xiphostoma.
F. Anostominae.—Herbivorous, entirely or partially; teeth well developed in both jaws; maxillary very small; gill-openings narrow; scales cycloid. American: Anostomus, Leporinus, Characidium, Chorimycterus, Nanostomus, Nanognathus.