APRIL, 1908. LAKES AMATITLAN AND ATITLAN MEEK. 173 



to some extent a body of partially stagnant water. In the lower 

 portion there is a constant flowing in of a considerable amount of 

 water at its upper portion, and a constant outflow at the opposite 

 end. This would tend to decrease the quantity of any floating parti- 

 cles in the water. Much of the algae floats on or near the surface. 

 It is often driven together by the wind, forming on the surface of the 

 lake large, blue-green patches. The alga? to which these species are 

 most nearly related form a large portion of the food supply for micro- 

 scopic animal life, and for small fishes which feed on vegetation. The 

 Algae and softer portions of the other water plants furnish a large part 

 of the food supply for the young fishes, and also for the adult of the 

 three most abundant species of fishes (Pescadito, Serica, and Mojarra) 

 in the lake. 



The water of Lake Atitlan is very clear as compared with that of 

 Lake Amatitlan and, as noted above, the amount of Plankton material 

 in it is very much less. 



So far as I could discover there are no diseases among the fishes of 

 Lake Amatitlan. The Mojarras are occasionally infested with intes- 

 tinal parasites, but the fishes appear in good condition, which indicates 

 that these do no harm. Parasites are occasionally noticed in the other 

 species of fishes in the lake. Intestinal parasites are not uncommon 

 with fishes and other animals, and their presence is not to be regarded 

 as an indication of ill health or disease. In our northern waters there 

 are occasionally epidemics among fishes during which many dead and 

 dying are found along the shore. I was unable to learn of any similar 

 epidemic among the fishes of Lake Amatitlan. If such ever occur 

 they are not at all frequent or serious. During my stay at the lake all 

 animal and plant life in the lake appeared vigorous and healthy. The 

 uniform temperature of the water, the freedom from sewage, and the 

 large volume of water, are all factors which induce a very healthful 

 condition in this body of water. An over supply of plant life contri- 

 butes largely to eliminate from the lake the noxious gases formed from 

 any decomposition of animal or vegetable life, and to take up the 

 waste products of water animals. 



The conditions of Lake Amatitlan, its fish food supply, the tem- 

 perature and purity of its water, etc., are such that it should contain a 

 far greater number of large fishes than it does at present. In general, 

 the fishes which feed on animal life are superior as food for man to 

 those whose food consists mostly or entirely of plants; and it is this 

 class of the larger fishes that is lacking in the lake. The smaller 

 fishes, especially the Pescadito, are very abundant, and it seems best 

 to introduce a few large species into the lake which would utilize these 



