The study was conducted to assess the growth and production performance of shrimp and rajpunti under mixed culture at various stocking ratios in Bagerhat district over a four-month period from March to July 2023. The experiment used randomized block design (RBD) and was designed with three treatments based on stocking ratio. Shrimp (Penaeus monodon) post larvae and fingerlings of rajpunti (Barbodes gonionotus) were stocked at a ratio of 4:3, 4:5, and 4:7/m2 in T1, T2, and T3, respectively. Shrimp and rajpunti were fed commercial diets and farm-made formulated feeds on a regular basis. Different water quality parameter was measured at ten day intervals. There were no significant differences (p > 0.05) in water quality parameters among all treatments. Higher final weight of shrimp was found in T2 (28.15 g) than T1 (27.39 g) or T3 (25.36 g). Rajpunti growth and survival rate were lower in T3, which had a high stocking ratio. T1 had higher shrimp production (674.34 kg/ha) than T2 (632.44 kg/ha) and T3 (488.24 kg/ha). Rajpunti production was substantially greater (p < 0.05) in T2 (1511.10 kg/ha) and T3 (1470.09 kg/ha) compared to T1 (923.06 kg/ha). However, the combined output and net profit of shrimp and rajpunti farming were considerably (p < 0.05) greater in T2 (2143.54 kg/ha, BDT 212309.10/ha) followed by T3 (1958.34 kg/ha, BDT 162831.50/ha) and T1 (1594.10 kg/ha, BDT 160845.90/ha). Therefore, the inclusion of rajpunti with shrimp at a stocking ratio of 4:5/m2 is recommended for dissemination among shrimp farmers in order to accelerate production while also generating a high economic benefit.

Keywords: Penaeus monodon, Barbodes gonionotus, stocking ratio, production, profit

The effects of washing treatment on hatching rate of eggs and survival rate of nauplii and postlarvae (PL) of Penaeus monodon was studied at a commercial hatchery of Bangladesh during the period of November 2008 to October 2009. The experiment was set up with two groups for each of P. monodon eggs, nauplii and PL, viz., i) washing treatment (treated group), and ii) without washing treatment (control group) in triplicate. The hatching, nauplii and PL survival rates were significantly higher (p<0.05) in treated group over those of control group. The mean hatching, nauplii and PL survival rates were 76.6±13.2, 76.4±8.7 and 79.6±9.1% in treated group and 30.0±6.9, 48.8±7.0 and 53.8±8.7% in control group, respectively. Hatching and survival rates of nauplii and PL were noted with better performance in winter, spring and autumn than that in summer. The observations from this study could be useful for larval rearing of P. monodon in areas where shrimp hatchery system is a promising industry.

Keywords: Penaeus monodon, hatching, larval rearing, washing treatment