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SPECKLED DACE, Rhinichthys osculus (Girard) This fish is one of the most abundant and wide- spread minnows in western United States, living in a variety of places-cold mountain creeks, silty rivers, fast and slow-moving waters, isolated hot springs, etc. The color pattern is very variable, sometimes showing one or two dark bands on the side but just as often lacking either of these and being speckled or blotched. It is rarely taken in water over three feet deep and is common about rocky riffles. The speckled dace is an important source of food for predatory fishes (such as trout) because it is both common and of small size, usually two to three inches long. It is also valued as a baitfish. The scales are rather small and if one is removed and observed under a microscope it will be seen that lines (called radii) radiate outward from its center like the spokes of a wheel. The speckled dace eats green algae and aquatic insects and other such small organisms. FATHEAD MINNOW, Pimephales promelas Rafinesque This species, native to eastern North America, is an important baitfish in many parts of the United States and is readily eaten by game fishes such as bass. Males are about 3 inches and females 2 inches long; both sexes live for approximately 2 years. The breeding season extends from May to late August and spawning generally does not occur until the water temperature reaches 64° F. A nesting site on the underside of some object is carefully chosen and guarded by the male, and several females deposit their eggs there. The male develops a dark spongy pad on his back with which he strokes the eggs while swimming back and forth beneath them. This proce- dure keeps the surface of the eggs free of silt so that they can absorb an adequate supply of oxygen from the water. As many as 12,000 eggs may be deposited in one nest; they hatch in 4 to 6 days. The fathead minnow prefers the slowly moving water of sluggish creeks, lakes, bogs, and ponds; the water may be clear or silty, cool or warm. SUCKER FAMILY CATOSTOMIDAE The suckers are often regarded as worthless fishes -perhaps because they have little aesthetic appeal and are full of small bones that make them difficult to eat. They are closely related to minnows but com- prise far fewer species (only about 80) that, with two exceptions in Asia, are confined to North America. As the name implies, the mouth is especially fitted for sucking, and the lips may have sharp, horny sheaths that enable the fish to scrape green algae from rocks. In the spring, suckers usually migrate upstream to spawn. Some species in the eastern United States are of commercial importance and the Utah sucker (Catostomus ardens) was formerly netted in large numbers in Utah Lake. The young are impor- tant in the diet -of predatory food and game fishes and several species have been used for bait. r' - Insert shows ventral view of mouth. 27 f-LANNEL MOUTH SUCKER Insert shows scale.