Influence of juvenile stunting on grow-out performance of rohu, Labeo rohita (Hamilton, 1822)

Abstract

Summary Rohu Labeo rohita juveniles stunted for 2, 4, 6, 8 10 and 12 months at 20 and 40 m−3 densities were subsequently cultured for 1 year in six grow‐out earthen ponds each 0.09 ha. Each pond was stocked with juveniles stunted for a particular duration (treatment) at a combined density of 8,000 ha−1 from two density groups at a 1:1 ratio. Electronic tags were implanted in 20 juveniles of each density group in all treatments as sub‐samples to track fish growth per individual. Another grow‐out study evaluated the growth of a fresh batch of rohu juveniles against similar sized but stunted 12‐month‐old juveniles, stocked together at 8,000 ha−1 density (1:1). Thirty juveniles from each group in this pond were tagged. After the year‐long grow‐out phase, survival (85.6%–96.3%) showed a positive correlation with the juvenile stunting duration. The study revealed a minimal influence of stunting density on juvenile growth in a subsequent grow‐out phase when they were stunted up to 8 months. But a higher stunting density (40 m−3) favoured growth in juveniles stunted for longer periods (>8 months). Growth curves of the lower and higher stunting density groups as well as “all rohu populations” in the treatments showed convergence with those of control (2 months stunted) only in the 4‐month stunted juveniles. The growth convergence in this treatment was achieved within 6 months of culture and subsequently surpassed that of control to over‐compensate at the end of 12 months of culture. No such compensatory growth (CG) response was observed in the 6‐ to 12‐month stunted rohu, because the growth curves run almost parallel to each other. The study also revealed juvenile stunting for more than 6 months delayed the initiation of the growth recovery process in the stunted individuals during their subsequent grow‐out phase. In the second study, identical growth trajectories of the fresh batch and the year‐long stunted juveniles reaffirmed a non‐existence of CG activity in the later. Such results indicate that juvenile stunting in rohu for 6 months and beyond does not lead to a better fish yield or economic gain to farmers, but rather adds to the investment costs because of the need for more feed and maintenance during stunting.

Growth performance of pengba,Osteobrama belangeri(Valenciennes, 1844) and water quality changes during fingerling rearing with varied stocking density in large outdoor concrete tanks

“…In present study, while survival significantly reduced with crowding, marked response in terms of lowered length and weight gain with increased density could be observed as early as on 15-d ( Figure 1). Similar growth suppression due to higher stocking density during juvenile rearing has been reported earlier in sea bream (Montero, Izquierdo, Tort, Robaina, & Vergara, 1999), in mono-sex tilapia (Little, Bhujel, & Pham, 2003) and in rohu (Das, Mishra, Mishra, & Jayasankar, 2016). Similar growth suppression due to higher stocking density during juvenile rearing has been reported earlier in sea bream (Montero, Izquierdo, Tort, Robaina, & Vergara, 1999), in mono-sex tilapia (Little, Bhujel, & Pham, 2003) and in rohu (Das, Mishra, Mishra, & Jayasankar, 2016).…”

“…Widening of the growth difference in subsequent period, as also the significant reductions of ABW and SGR with increased densities at the end of rearing phase (Table ), also demonstrated the noticeable effect of crowding on growth of fingerlings. Similar growth suppression due to higher stocking density during juvenile rearing has been reported earlier in sea bream (Montero, Izquierdo, Tort, Robaina, & Vergara, ), in mono‐sex tilapia (Little, Bhujel, & Pham, ) and in rohu (Das, Mishra, Mishra, & Jayasankar, ). Vijayan and Leatherland () had reported an inverse relation of stocking density with feed conversion efficiency and growth in brook charr ( Salvelinus fontinalis ).…”

Duration of stunting impacts compensatory growth and carcass quality of farmed milkfish, Chanos chanos (Forsskal, 1775) under field conditions

“…Lower body weight gain and SGR were observed in T12 group which indicates that prolonged stunting negatively affects the growth of milkfish. Similar to this, stunting of rohu for more than 6 months negatively affects its growth performance in the grow-out phase 65 .…”

Assessment of compensatory growth in stunted fingerlings of Snubnose pompano, Trachinotus blochii (Lacepede, 1801), in marine conditions

“…Duration of stunting is an important factor that determines the degree of compensatory growth. Das et al, (2016) growth of silver pompano in tropical marine conditions (Abdul Nazar et al, 2012).…”