The observations on the breeding habits of Cyprinidae and Siluridae were carried on in their natural spawning grounds from 1921-1923, while of Ophiocephalidae were recorded from Departmental ponds at Madhopur and Sirkian. The measurements and weight of gravid females were taker, and the total number of eggs obtained by weighing the whole mass and then weighing a small portion carefully and counting it as a basis for a calculation.
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Members of the Ophiocephalidae have successfully bred in artificial waters and they are mainly tank fishes. the enormous production of eggs in Cyprinidae and Siluridae is in adaptation to their environmental conditions which allow hardly one out of thousand eggs to develop,while in Ophiocephalidae , formation of nests, parental care and absence of floods play a great part protecting the small number of eggs - two to seven thousands - which are laid before the rains set in. The observations recorded here were ruad e at ther Departmental Hatcheries on Ophiocephalus marulius mainly and O. gachua and O. striatus occasionally.
Nest building of O. striatus of Ceylon has been described by Willey 1 , and of O. striatus of Mysore by Day 2 and of O. punctatus of Madras by Wilson. Ophiocephalus marulius makes its nest amongst aquatic plants and in spots, where there is abundarice of food for young fry. Just before the eggs are laid the fish may be seen swimming towards the banks and biding themselves under vegetation: they are seen in pairs. A pair is often seen to frequent only one place, where later on the nest is made by means of cut portions of weeds which the fish break or uproot, with their mouths. It takes at least a week to build up a nest: which is merely a receptacle for the eggs without any elaborate passages for ingress or egress of fish; and both male and female take part in its construction.
Process of spawning has been observed in Ophiocephalus gachua . The pair lies submerged in clear, but stagnant, water without any nest or receptacle. The female has its ventral surface directed upwards, while male lies crosswise over it. Their genital pores are thus close together. Two to three hundred eggs are liberated at a time at an intervals of a minute or two, and the fish remain in the same position, and at the same place till all the eggs have come out. The male pours its milt at the same time. Eggs rise to the surface, spread there and float. The fish use their fins all the time to keep their balance. 3
Eggs in Ophiocephalus marulius are floating, circular, light. reddish yellow and non-adhesive. There is a single large oil globule in the yolk which makes the egg bouyant. Each egg measures 2 mm. There is no gelatinous covering. The embryonic development goes on rapidly, but depends considerably on the temperature of water. The eggs hatched out in fifty four hours at temperature 61° to 79° F and in thirty hours where the temperature ranged from 83° to 92° F.
The breeding season of Ophiocephalidae in the Punjab lasts from the middle of April to the end of July. The fish guard their fry for about a month or so. In the case of O. marulius six weeks old fry do not keep together and probably when the fish find its young ones have become disobedient and have begun to wander about, it begins to devour them.
Whether it is the male or female that guards the nest is an open question. The female has been frequently seen just beneath the eggs and fry, keeping strict guard over them and is easily recognised by its large size. the male keeps watch at a short distance, and whenever the nest is approached, the male runs away causing a splashing noise which warns the female. The female does not run away immediately but keeps looking at the intruder and withdraws herself backwards slowly, keeping an eye on the nest at the same time. The positions of male and female are very often reversed. For full one week the fry remain in the nest, and then the parent fishes take them alongwith them. The fry sometimes separate into several groups, but the parents stay at one place and each group comes back as though they have been ordered to do so. In one instance the parent fish jumped a foot clear out of water after a kingfisher, which after taking a fry had flown to a branch of a tree a yard above the surface of water. When the fry grow big and are too numerous to be guarded by the mother alone, they split up into two groups, one guarded by the male and the other by the female. The fish at this stage when approached would either bide itself under its young ones or would leave them very reluctantly, going not far off, and returning soon after the intruder had gone away. A pair of Ophiocephalus gachua were once seen in a pond with a few days old fry. The male swam immediately below the swarm while the female was at a little distance off. Positions were, however, frequently reversed, and the female as often remained below while the male kept watch on one side or the other, swimming round and round. Two Belone cancilla made their appearance, evidently attracted by the fry, but were met with by the angry eye of the mother. Both intruders came to a halt and remained as motionless as O. gachua , and a staring match ensued: both being absolutely motionless for the space of quite a minute or more, though not nine inches of water divided them. At length a very slight fin movement of O. gachua sent her slightly forward and like a flash both the Belone rancilla turned about and made off, while O. gachua returned to her brood. Both the Belone rancilla were considerably longer than the O. gachua which sent them about their business.
1 Willey A. Observations on the nests, eggs and larvae of Ophiocephalus striatus. Spolia Zeylanica, Vol. vi. PT. 22, dec. 1909, pp. 108 - 123 . Back
2 Day F. Fauna of British India, Fishes. Back
3 We really wonder whether he really had seen O. gachua . In the 80's G. Ettrich found out, that O. gachua as well as C. orientalis is a mouth-brooder. Back
This text was originally published under the above title in The Journal of the Bombay Natural History Society , vol. 29, part 4, pp. 958-963, 1924.
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