Becker, George C. / Fishes of Wisconsin
Minnow and carp family - cyprinidae, pp. 415-605 ff. PDF (93.4 MB)
604 Minnow and Carp Family-Cyprinidae summer of life (age I), and some individuals probably do not mature until their third summer (age II). Age- III fish rarely appear in collections (Carlson 1967, Held and Peterka 1974, Chadwick 1976). The largest fatheads observed, 90-101 mm TL, were reported from Smithys Lake (Nebraska) (Mc- Carraher and Thomas 1968). The fathead minnow is an opportunistic feeder. In northern Wisconsin ponds, the stomach contents of fatheads consisted of algae, fragments of higher plants, and mud (Williamson 1939). In southeastern Wisconsin (Cahn 1927), the fathead was observed to be a bottom feeder, grubbing in the soft bottom for insect larvae, which formed over 90% of its diet. In a Missouri pond (Divine 1968), fathead min- nows less than 35 mm long ate a variety of foods, including higher plant materials, filamentous algae, and colonial algae. In another pond, the dominant food item changed each month: filamentous algae (Spirogyra, Mougeotia) in June, copepods in July, Cla- docera in August, and insects in September. All larger fish consumed a greater variety of organisms, including-in addition to those mentioned above- protozoans, rotifers, and insects; insects constituted more than 85% of the diet in August. The upper limit of the fathead minnow's temper- ature tolerance (permitting 50% survival) is 33°C (91.4°F); the lower limit is 2°C (35.6°F) (Bardach et al. 1966). Temperature preference, determined experi- mentally, was 22.6°C (72.7°F) (Jones and Irwin 1962). Brungs (1971) evaluated the chronic effects of con- stant elevated temperatures on this species: the num- ber of eggs produced per female, the number of eggs per spawning, and the number of spawnings per fe- male were gradually reduced at successively in- creased temperatures above 23.5°C (74.3°F). No spawning or mortality occurred at 32°C (89.6°F). The fathead minnow probably exhibits the great- est ecological diversity of all cyprinids occurring in North America. Cross (1967) referred to it as a "pioneer" (p. 151): ... It is one of the first species to invade intermittent drain- age channels after rains, and it commonly progresses up- stream into farm ponds via their spillways. It is one of the last species to disappear from small, muddy, isolated pools that remain in stream channels during droughts. This spe- cies has other attributes of hardiness that enable it to flour- ish where few other fish survive. It seems unusually toler- ant of pollution, in streams having little oxygen as a consequence of sewage influx or barnlot drainage, and in other streams that are saline owing to effluents discharged by the petroleum industry. The fathead is often found in lakes where most other species succumb to winterkill; it may survive in muskrat burrows at such times (Carlander 1969). It is tolerant of both clear and turbid waters, and of a wide range of pH. In Little Hemlock Creek (Wood County), 190 fat- head minnows were collected with these species: white sucker (75), blacknose dace (28), creek chub (75), pearl dace (6), northern redbelly dace (32), bluntnose minnow (13), common shiner (178), black- nose shiner (12), bigmouth shiner (6), brassy min- now (3), black bullhead (1), central mudminnow (13), blackside darter (1), johnny darter (13), pumpkin- seed (3), and brook stickleback (6). IMPORTANCE AND MANAGEMENT The fathead minnow is an ideal forage fish, since it is widely distributed, small, and highly prolific, and has a prolonged spawning period, assuring the avail- ability of recently hatched or small fatheads to preda- tors throughout the summer months. All fish-eating birds and fishes associated with it must at one time or another use this minnow as food. Isaak (1961) noted that large leeches and painted turtles prey on the eggs of fathead minnows and destroy many fat- head nests. The male's attempts to ward off these predators are futile. The fathead minnow is unable to maintain itself in streams or lakes which have a heavy population of predacious fish. In Wisconsin, the fathead is least common in streams which support numerous other kinds of fish; where the fathead does occur in such waters, it is generally found to be at depressed popu- lation levels. It becomes abundant in streams "pecu- liar in having emergent vegetation in pools, and a scarcity of other minnows" (Starrett 1950a). In Wisconsin, the fathead minnow is a major bait fish, available at most bait stations. It is ideal bait for crappies, perch, white and yellow bass, and rock bass; the largest adults are suitable for walleyes, bass, and larger game fish. The fathead is one of the hardiest of fishes, and, if hooked through the lips or the tail, or under the dorsal fin, it will stay alive for a number of hours. The fathead minnow has been used extensively as a testing animal, and culture units of fathead min- nows for this purpose are maintained at research laboratories (Benoit and Carlson 1977). Numerous studies of the effects of toxic substances on the fat- head minnow's body tissues, eggs, and fry are re- ported in the literature.
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