50 UNIVERSITY OF WISCONSIN STUDIES 



CONCLUSIONS 



Lake Valencia is a large lake which presents typical condi- 

 tions for the tropics. It becomes stratified during the summer 

 in relation to temperature and gaseous content. However, 

 the deep water contains sufficient oxygen for fishes and there is 

 considerable food present there. Its plankton is not abundant. 



The most fishes occur in shallow, littoral habitats. There 

 are no very large fishes in the lake and the number of fishes 

 present, as judged by the catch per hour in gill nets, is not as 

 great as in certain lakes in Wisconsin, which the writer has 

 investigated by methods like those used in studying this lake. 

 There is some evidence that the majority of the fishes were 

 originally inhabitants of rivers. In general the wide ranging 

 species feed on ubiquitous foods and are able to invade a 

 number of habitats. The foods eaten by the fishes in Lake 

 Valencia are, in the order of their importance: mud, immature 

 insects, plants, molluscs, fishes, adult insects, entomostracans, 

 oligochaetes, mites, and rotifers. The bottom and the aquatic 

 vegetation furnish most of the food and plankton is of little 

 importance. 



About twenty-three species of parasites occur in Valencian 

 fishes. In general the species of fishes which have the greatest 

 variety of habitats and foods are most infected. River fishes 

 have fewer parasites than those in the lake. 



