REPORT OF STATE BOARD OF PISH COMMISSIONERS. 85 



Cottus. Bullheads; Miller's Thumbs. 



The remaining species of fresh-water fishes are all small, and only 

 indirectly of economic interest. Our account of the one found at Lakes 

 Tahoe and Donner will serve for them all. 



Large individuals (about seven inches is large for this fish) are 

 especially abundant near the hatching house of the Fish Commission, 

 where the dead trout eggs are thrown each day. A handful of trout 

 eggs is certain to bring a bullhead from under every stone in the 

 vicinity. This fish is related to the Oligocottus analis, a marine speciee 

 of bullhead living in tide pools on the coast of California, which 

 changes, according to food and surroundings, from a grass-green to gray 

 of various patterns. The changes in color of Cottus minutus are no less 

 striking. Over a muddy bottom this species is quite black, assuming a 

 drab or "sand color" over sandy bottom; while over rocks and pebbles 

 it is conspicuously banded with light and dark. The bullheads are 

 very destructive to the trout. They lie in wait for them at the mouths 

 of creeks for the descent of the young ones. The bullheads, in their 

 turn, form the principal food of a species of Eutenia, abounding on the 

 shores of the lake. 



