106 



are laid under any flat object on the bottom in water 

 as deep a^ 8 feet. A depth of 6 inches to 3 feet is 

 preferred. A count of eggs in 10 females averaged 2,005 

 per fish. The eggs hatch in 7 to 15 dajfs. The young 

 reach marketable size by fall and spawn the following 

 spring. 



Maximum age is about 4 years. The blunt-nosed 

 minnow has been propagated in Michigan at the rate of 

 104,800 fish (250 pounds) an acre. In general, this 

 species seems less prolific than the fat-headed minnow, 

 but in Ohio 473, 350 an acre have been raised. This 

 species will not withstand crowding in minnow containers 

 so well as the fat-headed minnow. 



Because good keys for the separation of minnow 

 species were not available until recent years, much of 

 the literature and the records of stomach contents for 

 the blunt-nosed minnow have probably been confused with 

 those of the fat-headed minnow. More recent studies 

 indicate that the feeding habits of both these species 

 are similar; so the records, general as they are, could 

 apply to either species. 



The blunt-nosed minnow is known to eat diatoms, 

 algae, aquatic insects, entomostracans, fish eggs, fish 

 fry, and oligochaete worms. Occasionally this minnow 

 will eat its young. Some stomachs of the blunt— nosed 

 minnow contain only plant plankton; others, only surface 

 drift; and others, large percentages of insects, higher 

 plants, animal plankton, debris, or silt. A summary of 

 food studies by several workers shows that, in general, 

 the food percentages are: insects, 15.9; crustaceans, 

 3.5; entomostracans, 2.0; surface drift, 10.7; annelids, 

 0.5; animal plankton, 6.9; plant plankton, 35. 0;-plants, 

 8.7; algae anddiatoms, 4.9; and silt and debris, 11.8. 



Central stone-roller 



Cam-postoma anomalum Pullum (Agassiz) 



General description. — Plump, sturdyminnow, under- 

 slung suckerlike mouth with horny ridge forming the 

 lower lip; scales large, sometimes flecked with black 

 pigment; black crescent on dorsal fin of adults; large 

 tubercles on top of head of breeding mwles; lining of 

 abdominal cavity black, intestine very long and wound 

 spirally around air bladder. 



