18 UNIVERSITY OF WISCONSIN STUDIES 



FOOD OF FISHES 



It was the plan to study the food of ten individuals of each 

 species from each habitat in the lake. The following review 

 does not include food notes on all the fishes collected in the 

 Valencia basin but gives a good idea of all the common species 

 in the lake itself. Table V summarizes the results. In the 

 table and in the following notes lengths are given in millimeters 

 and do not include the tail fin. Numbers relating to foods 

 mean percentage by volume. In making examinations for 

 food the contents of the stomach and intestine were stripped 

 on a glass plate, the entire alimentary canal was then slit open 

 and any remaining materials taken. The food mass was teased 

 with needles under a binocular microscope, any small objects 

 being examined under a compound microscope. 



Aquidens pulcher (Gill), Chusco 



Isla del Euro; July 9, 10; number examined, 10; lengths, 

 105-62, ave. 97. Food: undetermined insect larvae 3.5; 

 chironomid larvae .9; chironomid pupae .1; fly 2; ostracods 9.5; 

 snails 83.5. 



Off rush-grown shore, 2.5 m., Maracay; July 22; no. ex., 5; 

 lengths 106-73, ave. 97. Food: fish 20; undetermined insect 

 larvae 19; chironomid larvae 9; ostracods .6; snails 45.4; 

 plants 6. 



Off rush-grown shore, Maracay, July 28, 12 m.; no. ex., 3; 

 lengths 90, 74, 77; ave. 80. Food: fish 42; chironomid larvae 

 28; ostracods 10; snails 20. 



Off rush-grown shore, Maracay, July 26; no. ex., 3; lengths 

 80, 80, 103, ave. 88. Food: fish 10; Tanypus larvae 35; 

 Tanytarsus larvae 5; Orthocladius larvae 1.7; snails 18.3; 

 plants 8.3; bottom 21.7. 



Mouth of Rio Bue, July 19, no. ex., 4 (2 empty); lengths 

 128-112, ave. 120. Food: fish 50; insects 50. 



Summary No. ex. 24; ave. length 92. Food: fish 16.3; 

 undetermined insect larvae 10.4; chironomid larvae 12; chirono- 



