Juvenile green guapote (Mayaheros beani) cultured at different salinities: effects on productive performance, proximal composition, blood biochemistry, and digestive capacity.

The green guapote Mayaheros beani is a fish of northwestern Mexico with importance as an edible and ornamental fish; however, there are still information gaps related to the physiological response of these fish under different environmental conditions. Therefore, the present study focused on studying the productive performance, proximal composition, blood biochemistry, and digestive capacity of juvenile M. beani (initial body weight: 2.56 ± 0.31 g) cultured at 0, 10, 20, and 30 practical salt units (PSU) (S0, S10, S20, and S30, respectively). After 8 weeks of testing, the weight gain (3.89 ± 0.35 g) and specific growth rate (1.68 ± 0.05 g/day) of the fish who received treatment S10 were significantly greater than those who received the other treatments. The best responses for feed conversion ratio and protein efficiency ratio were observed in those fish grown in salinities ≤ 10 PSU. Proximate analysis of the whole body revealed significant differences in dry matter content and total lipids between treatment S20 and S0, being higher in S0. Then, the highest levels of total protein (3.20 g/dL), globulin (1.77 g/dL), and cholesterol (348 mg/dL) in blood serum were recorded in fish grown in freshwater. Organisms subjected to the highest salinity (S30) had the highest values of proteases (243.7 U/mg), lipases (0.80 U/mg), and α-amylases (26.49 mU/mg) compared with levels of these enzymes recorded in fish at S0. These findings suggest culturing juvenile M. beani at salinities ≤ 10 PSU to avoid negatively affecting the growth, food use, or health of these organisms.