Effect of photoperiod and temperature on growth and activity of digestive enzymes in juveniles of the longarm river shrimp Macrobrachium tenellum (Smith, 1871) (Caridea: Palaemonidae)

We studied the influence of temperature and photoperiod on the growth, survival, and digestive enzyme activity of the juveniles of Macrobrachium tenellum (Smith, 1871) kept in tanks and fed with a diet containing 20% chitin. The regime of the 60-day experiment included two temperatures (26 °C and 30 °C) and two photoperiods (14L/10D and 10L/14D). In addition to survival, the evaluation included total growth, growth rate, specific growth rate, and feeding efficiency. Trypsin, chymotrypsin, lipases, amylases, and chitinases were also measured. The optimal final weight and specific growth rate were the result of a combination of photoperiod 14L/10D at both temperatures. There was no significant effect on survival. Among the enzymes tested for digestive activity, only chitinase in the 14L/10D treatment at a temperature of 30 °C proved to be significant.