NO. 5 (1920) CICHL1D FISHES OF MALABAR 163 



less, but the auditory organ is distinctly developed. The yolk is 

 richly pigmented. The larvae group together in the centre of the 

 pit and attaching themselves to small particles of sand by means 

 of the cement organs, they incessantly vibrate their tail. If dis- 

 turbed, they move about with the yolk sac upwards and soon 

 rearrange themselves as before. The instinct to group together 

 and to vibrate the tail lasts till the yolk sac is fully absorbed. 



Second day. — Pigment in the eye appears. 



Third day. — 6 mm. long. The mouth opens, and the yolk sac is 

 reduced to half its size ; a dilatation in front of the yolk sac at the 

 cardiac region appears. Heart beating is more vigorous and the 

 respiratory movements begin. 



Fourth day. — Pectoral fins appear, colour pigments appear on 

 the back at two centres. 



Fifth day. — The yolk sac is almost absorbed, dilatation in front 

 of the yolk sac disappears and when the larva moves, it lies over 

 on one side. 



Seventh day. — 7 mm. long, yolk sac wholly absorbed, tail fin 

 still continuous with the dorsal and ventral ; the larva leaves the 

 nest and moves about in its neighbourhood, guided by the mother, 

 in quest of food. Cement organs wholly disappear. 



Late larval stage. — The larva even after leaving the nest is quite 

 different from the adult fish in form. The tail remains long and 

 the caudal fin is continuous with the dorsal and anal. These fins 

 begin to separate only from the fourth day after the larva has 

 entered the second stage. About a fortnight afterwards, the pri- 

 mary chromatophores on th.e back disappear and permanent colour 

 bands begin to appear. The larva assumes the adult form within 

 a month after hatching, when it is about 18 mm. long. The 

 ocellus on the soft rays of the dorsal fin appears distinctly. The 

 young ones continue to be guided by the parents till they are 

 about an inch and a quarter long, which size they attain in about 

 two months. Even when they are out of the care of the parents 

 they group together in shallow places. 



Until the larvae attain the adult form and the bones develop 

 they are preyed upon by both young and grown-up individuals of 

 the same species. The larval nest is sometimes attacked by them 

 in groups, especially when they are kept under confinement. The 

 parents attempt to defend the nest by moving round it in circles, 

 but they are pushed aside and the nest is emptied of its contents. 



