Captive breeding, developmental biology and commercial production of Dravidia fasciata- An indigenous ornamental fish of the Western Ghats of India

Ornamental fishes of the Western Ghats of India have great demand in the export market. At present these fishes are collected from the wild and exported. Hence many times, the demand could not be met due to short supply. The only remedial measure for a sustainable supply is to produce the fish in captive conditions. Unfortunately, the breeding technology for the ornamental fishes of the Western Ghats of India has not been attempted seriously till date. The present paper is almost a pioneering attempt to develop captive breeding technology for 12 prioritized species of the indigenous ornamental fishes of the Western Ghats of India. Dravidia fasciata is one of them. It is popularly known as Melon barb. It is a beautiful barb, growing to a maximum size of 80 mm. In the present paper the methodology of captive breeding of this fish is provided with the economics of its production. Melon barbs were collected from the wild and brought to the hatchery of College of Fisheries in oxygen filled plastic bags and gradually acclimatized to the captive conditions. Its size at first maturity, sexual dimorphism, and developmental biology were studied and described with photographs. The total length (TL) at first maturity for males was 50 mm (50-55 mm) and 40 mm for females (40-45 mm). A sexually mature male developed beautiful pinkish red tinge all over the body. The black bands over the body also became deeper in colour during this time. The intensity of the colour reached its maximum during the courtship activities. Male also possessed nuptial tubercles on the operculum which could be identified only by keen observation. But a sexually mature female did not develop any colour change by the onset of sexual maturity. The results of the study clearly demonstrated that D. fasciata could be successfully produced in captivity through scientific management of brooders, eggs, larvae and hatchlings. The successful development of captive breeding technology is likely to pave way towards commercialization of the technology thus leading to the sustainable export of the species

Studies on the cranial osteology of the blind catfish Horoglanis krishnai Menon (Pisces, Clariidae).

Horaglanis krishnai Menon is a blind catfish inhabiting the dug- out wells at Kottayam, Kerala, South India. Studies on the cranial osteology of the fish show that the bones on the skull are firmly articulated. The frontoparietal fontanella is very large so that the cranium virtually lacks a roof. The sphenotics and alisphenoids are hardly recognizable and the orbital bones are entirely lacking. In osteological features H. krishnai closely resembles Uegitglanis zammaroni. But in H. krishnai the orbital bones are further reduced or even absent. The fontanella is larger than that of any other known catfish. These two species must have evolved from the same ancester and have taken up nearly identical ways of life. The difference between the skeletons of these two appears to be largely dependent on the relative size of the frontoparietal fontanella. Its greater development in H. krishnai brought about a suppression or reduction of some of the bones clearly visible in Uegitglanis. It would appear that the modification initiated in Uegitglanis gatered momentum in Horaglanis. These two fishes form a group distinct from clariids and bagrids but form a connecting link between the two

Use of tricaine methanesulfonate (MS-222) to induce anaesthesia in <i>Puntius denisonii</i> (Day, 1865) (Teleostei: Cypriniformes: Cyprinidae), a threatened barb of the Western Ghats, India

Anaesthesia is essential to minimize stress and physical damage during handling of fish in captivity. In the present study, induction time in Puntius denisonii (Day, 1865), an endangered aquarium fish exposed to four concentrations of MS-222 (50 mg L-1, 100 mg L-1, 150 mg L-1 and 200 mg L-1) was determined. MS-222 appears to be highly effective as an anaesthetic with no side effects to both fish as well as humans. An induction time of less than or equal to three minutes, and a complete recovery in five minutes was used a basis to record the anaesthesia stages for different doses. The onsets of individual phases of anaesthesia and recovery stages were also studied. Concentration of 150mg L -1 (induction 165 plus or minus 10 seconds and recovery time 112 plus or minus 10 seconds) was determined as the lowest concentration that induces anaesthesia in P. denisonii in less than three minutes. Induction and recovery times were dose-dependent. An inversely proportional relationship was observed between concentrations of anaesthetic and induction time. This is the first study to investigate the efficacy of different concentrations of MS-222 in Puntius denisonii and will be helpful to develop standardised techniques for transportation, captive breeding and other ex-situ conservation plans for this endangered and endemic barb

Studies on certain aspects of behaviour in the blind catfish Horaglanis krishnai Menon.

Horaglanis krishnai is a blind catfish inhabiting the dug-out wells at Kottayam, Kerala. This fish has great zoogeographical importance as a similar blind clariid, Uegitglanis zammaroni is found only in the artesian wells of the former Italian Somaliland. Studies on certain behavioural aspects of the fish in captive conditions showed that, this fish even though is blind, exhibited a high degree of thigmotactism. Locomotion, comfort behaviour, feeding and light sensitivity of the fish were studied under laboratory conditions. Though the fish is totally blind and histological study did not reveal the presence of any light sensitive structures, the fish is found to be sensitive to light stimulus. It is a predator. Under laboratory conditions it unerringly snapped up food organisms. This is obviously facilitated by the high degree of development of the tactile and olfactory sense organs