In size the suckers range from six inches in length to about three feet. As food-fishes they are held in low esteem, the flesh of all being flavorless and excessively full of small bones. Most of them are sluggish fishes; they inhabit all sorts of streams, lakes, and ponds, but even when in mountain brooks they gather in the eddies and places of greatest depth and least current. They feed on insects and small aquatic animals, and also on mud, taking in their food by suction. They are not very tenacious of life. Most of the species swarm in the spring in shallow waters. In the spawning season they migrate up smaller streams than those otherwise inhabited by them. The large species move from the large rivers into smaller ones; the small brook species go into smaller brooks. In some cases the males in spring develop black or red pigment on the body or fins, and in many cases tubercles similar to those found in the _Cyprinidæ_ appear on the head, body, and anal and caudal fins. [Illustration: FIG. 135.—Buffalo-fish, _Ictiobus cyprinella_ (Cuv. & Val.). Normal, Ill. ] [Illustration: FIG. 136.—Carp-sucker, _Carpiodes cyprinus_ (Le Sueur). Havre de Grace. ] The buffalo-fishes and carp-suckers, constituting the genera _Ictiobus_ and _Carpiodes_, are the largest of the _Catostomidæ_, and bear a considerable resemblance to the carp. They have the dorsal fin many rayed and the scales large and coarse. They abound in the large rivers and lakes between the Rocky Mountains and the Alleghanies, one species being found in Central America and a species of a closely related genus (_Myxocyprinus asiaticus_) being reported from eastern Asia. They rarely ascend the smaller rivers except for the purpose of spawning. Although so abundant in the Mississippi Valley as to be of importance commercially, they are very inferior as food-fishes, being coarse and bony. The genus _Cycleptu_s contains the black-horse, or Missouri sucker, a peculiar species with a small head, elongate body, and jet-black coloration, which comes up the smaller rivers tributary to the Mississippi and Ohio in large numbers in the spring. Most of the other suckers belong to the genera _Catostomus_ and _Moxostoma_, the latter with the large-toothed _Placopharynx_ being known, from the red color of the fins, as red-horse, the former as sucker. Some of the species are very widely distributed, two of them (_Catostomus commersoni_, _Erimyzon sucetta_) being found in almost every stream east of the Rocky Mountains and _Catostomus catostomus_ throughout Canada to the Arctic Sea. The most peculiar of the suckers in appearance is the harelip sucker (_Quassilabia lacera_) of the Western rivers. Very singular in form is the humpback or razor-back sucker of the Colorado, _Xyrauchen cypho_. [Illustration: FIG. 137.—Common Sucker, _Catostomus commersoni_ (Le Sueur). Ecorse, Mich. ] [Illustration: