No abstract

A 10‐week feeding trial was conducted to evaluate the effects of dietary replacement of fish oil (FO) with black soldier fly larvae oil (BSFLO) and vegetable oils, namely moringa oil (MO), black cumin seed oil (BCSO) and flax seed oil (FSO) on growth and whole‐body fatty acid profile, digestive enzyme activity, haemato‐biochemical responses and muscle growth‐related gene expression of juvenile striped catfish, Pangasianodon hypophthalmus. Five isonitrogenous (313.34 g kg−1) and isolipidic (81.82 g kg−1) experimental diets were formulated. A total of 450 fingerlings (5.02 ± 0.1 g per fish) were randomly distributed into 15 tanks and fed thrice a day. The final weight gain was significantly improved in fish fed FO (45.7 ± 0.72 g/fish), BSFLO (45.53 ± 1.32 g/fish) and MO diet (47.2 ± 0.26 g/fish) when compared to BCSO (36.3 ± 1.05 g/fish) and FSO (35.83 ± 0.71g/ fish) diets. The lower value of daily weight gain was recorded in the FSO and BCSO treatments compared with other oils could be due to effects on stress resistance and immunosuppression in fish, whereas the whole‐body EPA and DHA content of fish fed with FSO and FO diets was substantially higher than fish fed with other experimental diets. However, the relative expression of Myo D and Myogenin was upregulated in fish fed with FO, BSFLO and MO diet than the BCSO and FSO diet. Present results indicate that the juveniles can be reared on diets in which FO has been replaced with BSFLO and MO, with no significant effects on fish performance.

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India has enormous potential for the development of ornamental fish business. Although the country has conducive environmental conditions for breeding and culture of ornamental fishes, its share in export of ornamental fishes is less than 1%. The present study was undertaken to address the constraints prevailing in ornamental fish farming. Study was carried out among 44 ornamental fish farms in Madurai District, Tamil Nadu by adopting random sampling technique. The selected farms were classified into small (<0.5 ha) and medium farms (0.5-2 ha) and the data were collected by personally interviewing the fish farmers. The study attempted to analyse the socio-economic characteristics of respondents, existing supply chain, constraints involved in ornamental fish farming, annual revenue loss due to major constraints, treatment cost and expected profit margin. Various constraints were classified as production, marketing and others and were ranked using Garrett ranking technique. Tabular and percentage analyses were used to estimate the cost of treatment, revenue loss and expected profit margin. Four types of marketing channels were observed in the study area. Disease outbreak was found to be the major constraint faced by the farmers and hence, the revenue loss was estimated for the same. The annual revenue loss was found to be higher for the small ornamental units when compared to medium farms, which showed higher profit margin than small ornamental fish farms.