Three 8-week growth experiments were conducted to quantify the requirements of the fingerling Cirrhinus mrigala for the dietary branched-chain amino acids valine (experiment 1), isoleucine (experiment 2) and leucine (experiment 3). Six isonitrogenous (400/g) and isoenergetic (17·90k/) test diets were formulated with a gradation of 2·5/g for each test amino acid, valine (7·5–20/g), isoleucine (5·0–17·5/g) and leucine (7·5–20/g), and fed to randomly stocked fish in circular troughs. In experiment 1, the maximum weight gain (312%), best feed conversion ratio (FCR; 1·45) and best protein efficiency ratio (PER; 1·72) were obtained in fish fed 15·0g dietary valin/g. In experiment 2, the highest weight gain (317%), best FCR (1·47) and best PER (1·70) were recorded at 12·5g dietary isoleucin/g, and in experiment 3, the highest weight gain (308%), best FCR (1·46) and best PER (1·71) were noted at 15·0g dietary leucin/g. A quadratic regression analysis of weight gain, FCR and PER data showed an optimum requirement at 15·9, 15·0 and 14·8/g for valine, 13·2, 12·3 and 12·1/g for isoleucine and 15·6, 15·4 and 15·1/g for leucine in dry diets. Low body moisture and higher protein were noted in fish fed diets containing 15·5, 12·5 and 15·0g valine, isoleucine and leucine per kg, respectively. Body fat increased with increasing levels of the branched-chain amino acids. On the basis of a regression analysis of growth data, it is recommended that a diet for C. mrigala should contain valine at 15·2, isoleucine at 12·6 and leucine at 15·4/g dry diet, corresponding to 38·0, 31·5 and 38·5/g dietary protein, respectively.

De novo reference intervals (RIs) for a total of thirty two hematological and serum biochemical attributes were established for rainbow trout (Oncorhynchus mykiss) cultured in Himalayan aquaculture system. For this purpose, long term assessment of hemato-biochemical parameters was carried over a period of one year from March 2019 to February 2020 and a total of 444 blood samples were analysed. Blood examination results were recorded systematically and reference intervals were established, notably for erythrocyte parameters: hematocrit (Hct) 29–40%, hemoglobin 8.32–12.28 g/dL, red blood cell (RBC) count 1.01–2.04 (×10⁶/mm3); leukocyte parameters (x 10³/mm3): total leukocytes 31.32–90.60, neutrophils 4.21–18.85, total lymphocytes 20.55–63.63, small lymphocytes 14.86–46.50, large lymphocytes 6.35–22.34 and monocytes 1.22–7.56; thrombocyte count 23.00–68.00 (×10⁶/mm3). RIs were also established for red blood cell indices, vital serum constituents involved in carbohydrate, protein, lipid and nitrogen metabolism including the less known, diagnostically important, serum enzymes and electrolyte concentrations. Principal component analysis revealed that certain serum components were more efficient at distinguishing between the life stages (juvenile, adult) of fish by explaining about 92.7% of variation in the whole dataset compared to the principal hematological components which explained only about 80% of the variation. Significant (P < 0.05) differences were noted for RBC count, total leukocyte count (TLC), total protein, total cholesterol and uric acid with respect to the sex of fish. Moreover, clearly differentiable morphometric and morphological attributes were also noticed among erythrocytes, leukocytes (lymphocytes, neutrophils and monocytes) and thrombocytes. To our knowledge, the present study is the first of its kind that elucidates blood chemistry of cultured rainbow trout, O. mykiss in accordance to the guidelines framed by the American society of veterinary clinical pathologists (ASVCP). RIs reported here can help monitor the fish health status by improving the use of non-lethal diagnostics in piscine medicine.