36 Records of the Indian Miisevvi. [Vol. XIV, 



The bottom is composed of very soft, semi-liquid mud and there 

 are no rocks either at the edge or beneath the surface of the water. 



The temperature of the water never sinks as low as freezing point 

 and that of the bottom differs very little from that of the surface, which 

 remains fairly uniform throughout the twenty-four hours. We found 

 at the beginning of March that the surface temperature in the iniddle 

 of the lake was about 70° Fahrenheit. 



The water is heavily charged with lime. The following analysis 

 of a sample taken from the surface near the middle of the lake has 

 been made by Mr. R. V. Briggs, F.C.S., M.S.P.A. :— 



Per litre. 



Total solids ... ... ... ... ... 0-1710 



Organic matter ... ... ... ... ... 0-0160 



Calcium ... ... ... ... ... 0-0222 



Magnesium ... ... ... ... ... 0-0279 



Chlorine ... ... ... ... ... 0-0017 



Sulphate (804) ... ... ... ... ... 0-0017 



Silica ... ... ... ... ... 0-0010 



Carbonic acid (CO3) ... ... ... ... 0-1030 



Iron ... ... ••• ■■• Less than 1 part in 5 million. 



The edible fish of the lake are either rapacious in habits or else live 

 mainly on weed. There is an almost com2)lete absence of species that 

 feed on the surface. This is probably due in large measure to the clear 

 ness of the water, which is unfavourable to the growth of minute floating 

 organisms. At first sight the dense weed of the lake would seem to pro- 

 vide an ideal food-supply for vegetarian fishes, but as a matter of fact 

 a great part of the weed belongs to the genus Ceratophyllum, the horn}^ 

 nature of which is indicated in its name. It is very doubtful whether 

 this weed is reall}^ edible from the fishes' point of view. 



An important question in all fisheries is that of cover. Particularly 

 at the breeding season, it is necessary for the fish to hide themselves, and 

 as a rule they avoid bright sunhght. There is no lack of cover in the 

 Inle Lake and the horny nature of the most abundant weed is doubtless 

 beneficial from this point of view. The eagerness with which the fish 

 seek for cover is illustrated by several of the methods used in capturing 

 them. Another function that the weeds perform is that of providing 

 an abundant supply of oxygen. 



As in many well-populated districts, the chief enemy of the Inle 

 fish is man, but I do not think, as I will explain later, that his enmity 

 should at present be restrained. After man the most active agents 

 of destruction are rapacious fishes such as the snake-heads, which are 

 themselves among the most important species economically. Grulls, 

 cormorants and other piscivorous birds are fairly abundant, but 

 probably never excessively so ; the various ducks for which the lake is 

 famous amongst sportsmen cannot do much harm, as they feed chiefly 

 on weed and for the most part desert the lake before the main breeding- 

 season of the fish, in which they might do great damage by devouring the 

 spawn. Internal parasites rarely do appreciable harm to freshwater fish 

 living in natural conditions ; we found no trace of any parasitic disease 

 amona those of the lake. 



