164 MADRAS FISHERIES BULLETIN VOL. XII, 



Under natural conditions such determined attacks are very rare. 

 This cannibalistic tendency can be reduced by supplying them with 

 animal food in the form of chopped prawn or crab. E. maculatus, 

 gobies and crabs are other natural enemies to the larvae. If one of 

 the parents is separated, the other becomes disgusted with the 

 unaided care of the brood and soon wanders away leaving them to 

 themselves. The male can be easily allured by throwing food at a 

 distance, but the female takes the brood with her. The larvae, if 

 separated from the parents' care and reared under artificial condi- 

 tions, soon turn anaemic and die. 



Although these fish are found in large numbers near the mouths 

 of estuaries, none of them dares to enter the sea. When living 

 under adverse water conditions the fish turns more and more 

 blotched with black. The colour deepens with the increase of 

 salinity or density of the water. The same is the case when it is 

 put in water boiled and cooled and the colour becomes light when 

 the water is again well aerated. Although its adaptability to 

 varying conditions of salinity is wonderful, it is not immune to 

 bacterial or fungoid attacks. In one of my fish ponds into which 

 water percolates during the rainy season from the land side, bacte- 

 rial growth becomes enormous and the fish kept in it become 

 subject to the attack of a kind of bacterial disease and, if the pond 

 is not supplied daily with a current of saline water from the 

 adjoining backwater, all of them die within a few days. If the 

 affected fish are let out into the backwater they soon recover. 



Under favourable conditions within five years the fish grows to 

 rather more than a foot in length and weighs about three pounds. 

 Among backwater fishes it is the most esteemed in Travancore as 

 a food-fish and fetches the best price. 



2. ETROPLUS MACULATUS (Block). 

 Malayalam — Pallathi, Kurumpad =" Short striped." 

 This small cousin of E. suratensis is very common in all 

 waters of the plains of Malabar ; especially in paddy fields, shallow 

 canals and ditches. It migrates far higher up rivers and breeds 

 freely in them beyond tidal limits. In the power of endurance and 

 activity it surpasses its relative. Colour-change coincident with 

 alteration in the density of the water, is also marked in this species. 

 It moves about in schools consisting of individuals of different ages. 

 During the early part of the monsoon season after the first 



