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Abstract: Fingerling rearing of two minor carps fringe-lipped carp (Labeo fimbriatus), kuria labeo (Labeo gonius) and silver barb (Puntius gonionotus) along with the Indian major carp rohu (Labeo rohita) was carried out in outdoor concrete seed rearing system for 90days at four densities viz., 10, 20, 30 and 40m−2 to evaluate their relative growth performance and feasibility of polyculture during seed rearing. All the species except rohu showed more than 90% survival at all the densities and did not vary with regard to densities, whereas, rohu showed significantly lower survival of 64.5–66.8% in the two higher densities. Silver barb and kuria labeo showed higher growth potential than rohu and fringe-lipped carp while growth in the latter two was similar at all the densities. The study also revealed better fingerling production attributes, both in terms of number and biomass yield, at combined density of 40m−2 compared to 10–30m−2 and suggested the former to be ideal density for fingerling rearing of these species under polyculture in concrete tanks. [Copyright &y& Elsevier]

Nursery rearing of an endangered fish, Labeo gonius (Ham.) was studied in relation to varying stocking densities in earthen ponds. The experiment was conducted for 8 weeks in nine nursery ponds having an area of 0.012 ha with an average depth of 1 m. Four-day-old hatchling stocked at 0.6 million/ha was designated as treatment-1 (T1), 0.8 million/ha as treatment-2 (T2) and 1.0 million/ha as treatment-3 (T3), respectively. At stocking, all hatchlings were of same age group with a mean length and weight of 0.66 ± 0.08 cm and 0.001 ± 0.0001 g, respectively. Hatchlings in all the experimental ponds were given wheat flour for the first 7 days, finely ground mustard oilcake lot the next 7 days and a mixture of rice bran, and mustard oilcake (1 : 1) for days 15 to 56. The rate of feeding was 20 kg/million hatchling/day for the first two weeks. 25 kg for the second two weeks, 30 kg for the third two weeks and 35 kg for the fourth two weeks. The physicochemical parameters of water and plankton were monitored simultaneously and were within the acceptable range for fish culture. Growth parameters (final weight, final length, weight gain length gain and specific growth rate) and survival of fingerlings were significantly higher in T1 (0.6 million hatchling/ha) than those in T2 (0.8 million/ha) and T3 (1.0 million/ha), respectively. Feed conversion ratio (FCR) was significantly lower in T1 followed by T2 and T3 in that order. The estimated gross and net productions of fingerlings were significantly higher in T1 than in T2 and T3, respectively. Significantly higher number of fingerlings was produced in T3 than those in T2 and T1, Despite this, consistently higher net benefits were obtained from T1 than from T3 and T2. Overall, highest growth, survival, production and benefits were obtained from T1 where stocking density of hatchlings was 0.6 million/ha. Hence, of the treatments evaluated, stocking density of 0.6 million hatchling/ha appears to be the most efficient stocking density for rearing of L. gonius fingerlings in earthen nursery ponds. [ABSTRACT FROM AUTHOR]

Abstract The effects of periphyton, grown on bamboo substrates, on growth and production of two Indian major carps, rohu, Labeo rohita (Hamilton) and gonia, Labeo gonius (Linnaeus), were studied at the Bangladesh Agricultural University, Mymensingh. For each species, five ponds were provided with bamboo substrates and five ponds without substrate (control). Ponds were stocked at a rate of 10 000 ha[sup -1] in both treatments. There was no discernible difference in water quality parameters between treatments. A large number of plankton (39 genera) showed periphytic nature and colonized the bamboo substrates. Rohu grew faster, resulting in a 77% higher net production (P < 0.05) in the ponds with bamboo substrates compared with the ponds without substrate. In contrast, the growth and production of gonia did not vary significantly (P > 0.05) between the substrate and control ponds. Rohu seems to be a more suitable candidate for periphyton-based aquaculture systems than gonia. [ABSTRACT FROM AUTHOR]