Growth and survival of six stocks of rohu ( Labeo rohita, Hamilton) in mono and polyculture production systems

Abstract

One farmed stock (Local) and five riverine stocks of Rohu ( Labeo rohita, Hamilton) from 2-year classes (1993 and 1994) were evaluated for growth and survival under monoculture and polyculture systems at the Central Institute of Freshwater Aquaculture (CIFA), India. In the 1993 year-class, 29 full-sib groups of Local and 28 full-sib groups of river Ganga were tested while in the 1994 year-class the stocks tested were of Local and of rivers Brahmaputra, Ganga, Gomati, Sutlej and Yamuna with 6, 8, 7, 7, 18 and 11 full-sib groups, respectively. For each year-class, individually tagged fingerlings were stocked into three 0.1 ha monoculture ponds (9 fish/full-sib group/pond) and two 0.4 ha polyculture ponds (13 fish/full-sib group/pond). In polyculture, Rohu were stocked together with Catla ( Catla catla, Hamilton) and Mrigal ( Cirrhinus mrigala, Hamilton) in the ratio of 1.2:1:1, respectively. The stock effect on body weight at harvest was not significant in the 1993 year-class but highly significant in the 1994 year-class. The stock effect on survival from tagging to harvest was not significant in any of the year-classes. The interaction between production system and stock on growth and survival was significant but low, particularly compared to the significant and important full-sib effect. Thus, the growth performance of the stocks was relatively consistent in monoculture and polyculture. The significant full-sib effects for growth and survival suggest that these traits can be improved through selective breeding. The implications of the results for the development of a selective breeding program for Rohu in India are discussed.