Effect of Manganese and Iron on Growth and Feeding of Juvenile Giant River Prawn, Macrobrachium rosenbergii (De‐Man)

Abstract

Abstract.— The effect of either manganese or iron on survival, growth, and feeding of giant river prawn, Macrobrachium rosenbergii (De‐Man), juveniles was studied in two separate experiments. Survival rates of M. rosenbergii juveniles (4.58 ± 0.48 g) following 60‐d exposure to 0.01 (control), 0.3, 0.6, and 1.2 mg/L of total manganese (Mn) were 100, 93.3 ± 3.4, 83.3 ± 4.3, and 83.3 ± 4.3%, respectively, while the same were 100, 83.3 ± 3.6, 73.3 ± 3.3, and 63.3 ± 4.7%, respectively, at the total iron levels of 0.02 (control), 0.32, 0.65, and 1.2 mg/L. Average daily growth of the prawn was significantly (P < 0.05) lower at 0.3 mg/L and higher levels of total manganese compared to control (0.01 mg/L). Average growth of the prawn exposed to 0.65 and 1.2 mg/L total iron was significantly lower (P < 0.05) than in control (0.02 mg/L iron) and 0.32 mg/L treatments after 60 d of exposure. Feed utilization was significantly (P < 0.05) reduced in M. rosenbergii juveniles exposed to 0.3 mg/L and higher levels of manganese. Feed utilization was significantly (P < 0.05) reduced in the prawns at all the iron treatments compared to control (0.02 mg/L iron). The accumulation of Fe and Mn was minimum in the muscle and maximum in the hepatopancreas of the prawns.