1 72 Miscellaneous. 



Nidifimt'wn of the Indian Ramhow-Fish. 

 By M. Paul Carbonnter. 



The rainbow-fish (Colisa vulgaris, Cuv. & Val.) is met with in 

 the tanks and ditches of the country watered by the Ganges. Its 

 length never exceeds 4 centimetres. It is one of the prettiest of 

 known fishes. One is agreeably surprised with the exuberance of 

 colour that nature has bestowed upon this little animal ; but its 

 most important peculiarity, from a scientific point of view, is its 

 mode of nidification. 



As spawning-time approaches, the male, spreading his brilliant 

 fins, plays round the female, showing her his bright colours ; with 

 his long ventral filaments he pats and touches her in all directions, 

 until, overexcited by his caresses, she takes to flight. I believe 

 that all these graceful movements of the male fish, all these amorous 

 proceedings, influence the physical condition of the female and aid 

 the maturation of the ova. 



The male fish then commences the preparations for oviposition. 

 Seizing a little Conferva in his mouth, he carries it to the surface of 

 the water. The plant, from its greater density, would fall back 

 very rapidly to the bottom ; but our little workman sucks in a few 

 bubbles of air, which he divides and places immediately beneath 

 the plants so as to prevent them from descending. He repeats this 

 process several times, and thus, in the first day, forms a floating 

 island 8 centimetres in diameter. The bubbles of air are not 

 coated with a greasy liquid as in the case of the Macropoda chinensis ; 

 all those which approach sufficiently to touch, unite together and 

 fuse into one. 



The next day the male continues his provision of air, which he 

 now accumulates towards the central point. These bubbles exert a 

 pressure from below upwards, the consequence of which is the eleva- 

 tion of the vegetable disk, which, issuing from the water, becomes 

 converted into a sort of dome floating on the surface. 



The nest being completed outwardly, the fish busies himself with 

 giving it a firmness which may protect it from shipwreck. With 

 this view he creeps upon it in all directions, and glides over its walls 

 to smooth the surfaces ; he forcibly presses this felt with his muzzle 

 and his chest ; if one of the twigs is too prominent he seizes it and 

 removes it, or, by means of successive pushes with his head, forces 

 it into the interior. It is by turning and pressing the wall from all 

 sides that he succeeds in rounding it nicelj-. 



The protective roof being finished, the male plays about the female, 

 shows her the brilliancy of his dress, touches her with his appen- 

 dages, and seems to invite her to follow him. The female then 

 soon enters the nest. While she is feeling its walls and examines 

 its arrangement, the male, bent horizontally under the entrance, turns 

 spirally upon himself, throwing towards the summit of the edifice the 

 lustre of his many-coloured tints. 



Speedily the female approaches the male with confidence ; she 

 applies her head near the extremity of his anal fin, and thus tra- 



