Juveniles of the tropical ornamental fish, Discus (Symphysodon aequifasciatus) of mean standard length, 3.58 ± 0.03 cm and mean weight, 3.36 ± 0.03 g, were reared at four stocking densities (1 juvenile/10 L, 1 juvenile/7.5 L, 1 juvenile/5.0 L and 1 juvenile/2.5 L) with three replicates each, for a period of 12 weeks, to evaluate effect of stocking density on growth, condition index, size variation and survival. Growth and survival were recorded after every two weeks. At the end of the culture period, lower densities of 1 juvenile/10 L and 1 juvenile/7.5 L showed significantly higher growth and survival (p<0.05). The condition index and coefficient of variation did not vary significantly (p>0.05) among the stocking densities but coefficient of variation (CV) increased towards the end of the culture period. Results indicated that discus juveniles may be reared at the highest density of 1 juvenile per 2.5 l up to a period of two weeks without affecting growth parameters significantly, at a density of 1 juvenile per 5.0 l up to a period of six weeks and at a density of 1 juvenile per 7.5 l for a period of twelve weeks. It can, therefore, be concluded that a stocking density of 1 juvenile per 7.5 l is optimal for rearing juveniles of this fish without compromising on specific growth, survival and well-being.

total finfish production (FAO, 2020). Still, higher production can be achieved, but the unavailability of fry as a result of high mortality during the nursery rearing phase has been one of the major impediments in expanding its production. Generally, nursing of carp from spawn to fry stage is undertaken in small earthen ponds. With proper nursery management, where survival of 30%-40% of fry is

Use of probiotics in freshwater fishes is debated for its benefits to the host. Tinfoil barb, Barbonymus schwanenfeldii is a tropical fish having ornamental as well as food value. This study was conducted to evaluate effect of Lactobacillus sporogenes on Tinfoil barb. Diets containing 0%(T0), 0.5%(T1), 1%(T2), 1.5%(T3), and 2% (T4) of probiotic L. sporogenes were prepared and fed to fishes at 3% body weight for 80 days. Control diet was fed to fishes of all treatments for 20 more days. Growth parameters, gut microflora and intestinal histology were analysed. The growth performance was found to be significantly better (P < 0.05) in fishes fed with 1% of probiotic but Survival remained unaffected due to the concentration of probiotic. Total Plate Count of aerobes seemed to be affected by concentration and duration of probiotic treatment. However, anaerobic TPC did not show much variation. Histological analysis revealed that in lower level of incorporation (T2-1%) fish have intact mucosal layer with increased absorptive enterocytes and absorptive area of intestinal villi, well organized lamina propria with different types of cells compared to other treatments. The results indicated that addition of L. sporogenes at 1% level of inclusion was found to be effective for better growth, survival, gut flora as well as intestinal morphology in B. schwanenfeldii.

Mrigal or Cirrhinus mrigala (Hamilton 1822) is one of the important aquaculture species in India. During 2017, mrigal contributed 5.7% to the aquaculture production of India. The present study was undertaken to describe the hatchery-level pre- and post-spawning condition, i.e. weight changes in the length-weight relationships (LWRs) and the weight-weight relationships (WWRs) associated with the two phases for the mrigal males and females used as broodstock from a commercial IMC hatchery. For the 18 pairs of individuals sampled, the TL (total length) ranged from 42–55 cm and 39–54 cm, and the BW (body weight) from 0.83–1.46 kg and 0.52–1.35 kg respectively for males and females. The GSI was recorded at 10.5% for males and 20.4% for females. The pre- and post-pawning weights differed significantly in both sexes based on paired t-test. Trends in the LWR and weight-weight slopes have been discussed in the article.

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