1921.] S. L. HORA : Fish of Manipur. 169 



Nandidae and Percidae. The large number of species and in- 

 dividuals of the first three families, and especially of the family 

 Cyprinidae is a noteworthy feature of the fish-fauna of these 

 regions. iMoreover, the members of these families that live in hill 

 streams show certain adaptive characters which are dealt with in 

 detail under a separate heading. 



THE PHYSICAL AND OTHER CONDITIONS AS 

 THEY AFFECT THE FISH. 



In the general introduction to the fauna of the Manipur Valley, 

 Dr. N. Annandale has given an account of the L,oktak Lake. I 

 need here only mention a few of the features that seem to have a 

 special bearing on the fish-fauna. 



Dr. Annandale has referred to the luxuriance of vegetation 

 in the lake and has pointed out that it is blocked up to the sur- 

 face by a thick growth of Potaniogeton, Hydnlla and Trapa. From 

 the fact that no specimen of fish, more than a few inches in length, 

 was found in the lake, it is evident that this thick vegetation, 

 while providing food and shelter for the fish, is inimical to the 

 existence of big species, probably because it would retard their 

 progress and make them an easy prey to water-birds, otters, etc. 

 Cover plays a great part in the life of fish and the readiness with 

 which they seek it in the lake is fully illustrated by the devices 

 employed by the Manipuris in capturing them. 



Except the snake-headed fish {Ophioccphalus harcourt-butleri) 

 and three species of Siluridae, all the fish generally feed on aquatic 

 weeds, on small worms or insect larvae in the mud, vSurface- 

 feeding fish {Nga-ioa) though abundant in the streams of the valley 

 are totally absent from the lake. 



The destruction of fish brought about by man's agency is enor- 

 mous and in fishing Manipuris do not spare the small forms, which 

 only inhabit the lake. After man the most active agents of destruc- 

 tion are certain species of birds. The stomachs of a few cormo- 

 rants shot near Potsengbaum were found to be full of specimens of 

 Lepidocephalichthys bcrdmorei and Monopterus albus. Large num- 

 bers of these birds were often observed sitting on floating islands 

 and feeding on the fishes in the lake. The ducks and geese for 

 which this lake is famous among sportsmen do not appear to do 

 much harm, judging from the contents of their stomachs, unless it 

 be by destroying spawn. 



On dissection several species of fish were found to be infected 

 with round worms, but the degree of parasitisation was not very 

 high. 



The fish of the sluggish streams in the Manipur Valley com- 

 prise all those that live in the lake and include some of those the 

 proper habitat of which is the mountain torrents. It is not sur- 

 prising to find species of Glyptothovix, Garra, NcinachilHs and other 

 highly specialized genera in muddy streams when it is realised 

 that within a short distance a mountain torrent may become a 



