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Add To Calendar 29/04/2016 08:30:0029/04/2016 08:50:00Africa/JohannesburgAsian-Pacific Aquaculture 2016STRUCTURE OF THE TESTIS OF Sahyadria denisonii (Day) AN ENDEMIC AND THREATENED ORNAMENTAL CYPRINID OF THE WESTERN GHATS OF INDIA Diamond 5The World Aquaculture Societyjohnc@was.orgfalseanrl65yqlzh3g1q0dme13067DD/MM/YYYY

STRUCTURE OF THE TESTIS OF Sahyadria denisonii (Day) AN ENDEMIC AND THREATENED ORNAMENTAL CYPRINID OF THE WESTERN GHATS OF INDIA

Sajan. S* and Anna Mercy. T.V**
 
 School of Fisheries Resource Management and Harvest Technology, Faculty of Fisheries,
 Kerala University of Fisheries and Ocean Studies, Ernakulum, Kerala, 682 506, India.
 * sajanpolayil@gmail.com  
 **  annamercy2002@yahoo.co.in  (PRESENTING AUTHOR)

Reproductive strategies of fishes are extremely diverse and gonad development differs intra-specifically or inter-specifically depending on morphology or anatomy of gonad as well as environmental conditions. Therefore, a detailed study on the biological features of threatened species will be very important for implementing any fish conservation programme. Among the native ornamental fishes of the Western Ghats region of India, no species has received global fame and hobbyist attention as much as the Redline Torpedo fish, Sahyadria denisonii. Till to date, testicular maturation in S. denisonii has not been studied at the morphological or histological level. In the present study, an attempt was made in this direction to investigate morphology, histology and ultra structural biology of testis of this fish which may help in designing suitable conservation management strategies for this species.

Monthly samples of the fish were collected from the catch for aquarium trade at collection sites of River Valapattanam, Kerala, India. After assessing the stage of maturation, the testes were preserved in 5% formalin for further studies. Quantification of maturity stages was done by following and scheme proposed by El-Boray (2001). The fixed tissues were later processed by following standard procedures for histological and electron microscopic studies.

The male reproductive system in S. denisonii which is characterized by a pair of testis, ranged in length and weight from 1.6 to 4.1cm and 0.026 to 0.834gm respectively. Based on the shape, size, colour, texture and histological differentiations, eight maturity stages were recognized. They are immature virgin, early developing, late developing, mature, ripe, spawning, spent and developing recovery. Six stages of maturation were recorded during spermatogenesis as primary and secondary spermatogonia, primary and secondary spermatocytes, spermatids and spermatozoa.

A spermatozoon is characterized by ovoid head, a short mid piece, and a single flagellum, but the acrosome was absent. The present study indicated that S. denisonii has an anastomosing tubular type of testis with an unrestricted distribution of the spermatogonial cells. All the stages of spermatogenetic cells were distributed asynchronously and this type of cell maturity resulted in the discharge of sperms intermittently during spawning period. It may be concluded that S. denisonii had a prolonged spawning season. These descriptions are very important for a better understanding of reproductive biology, particularly of tropical fishes for which data remain scarce in the literature. This information has helped in the development of captive breeding technology of this fish by the authors.

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