Dec, 1921 rooD of ohio darters 61 



of the fish. Taking the food that they do and having the food 

 habits which are characteristic of them, it would not be 

 expected that Etheostoma flabellare and E. ccerideum would be 

 found in stagnant water. Nor on the other hand, would it be 

 expected that there would be found species like Cottogaster 

 copelaudi in swift brooks, when it is given to eating large 

 proportions of vegetation and debris. 



If any fish were able to adapt itself to several kinds of hab- 

 itats, it should be one of generalized habits, for specialized 

 habits whether food, reproductive or otherwise, limit the scope 

 of any animal. The wide range, uniform distribution, and 

 common occurrence of Percina caprodes are no doubt partly 

 due to the fact that the animal is unspecialized and is able to 

 become adapted to various habitats. The change in food 

 habits as Percina becomes a stream dweller, when it was 

 formerly a lake fish, may be cited as an instance of such an 

 adaptation in food behavior. 



SUMMARY. 



1. The food of the Ohio darters varies with the fishes. In 

 the most typical cases the young feed exclusively upon ento- 

 mostraca, turning to midge larvae and other small insect larvas 

 later, and when mature feeding upon a varied diet in which 

 ephemerid larvae and other large insect larvae predominate. 

 The fish with the most typical food habits is Percina caprodes. 



2. Some of the darters vary from this habit of eating insect 

 larvas in the younger stages b}^ apparently omitting the ento- 

 mostraca from the first stage. These fish are characterized, 

 even in the adult, by the large size of the food animals taken. 

 Etheostoma flabellare is the most specialized in this regard with 

 Etheostoma ca;rideiim resembling it. 



3. Other darters after passing through a rather typical 

 first and second stage eat a large percentage of vegetable 

 material and organic debris in their older stages. Cottogaster 

 copelandi is the most typical one of this group. 



4. Amphipods occur regularly in the food of most lake 

 specimens but are entirely lacking in those from streams. 



5. When members of a species are taken from both streams 

 and lakes there is a marked difference in the food animals 

 although there is usually a close adherence to the typical food 

 habit. 



