Effect of different stocking combinations on growth, production and survival of milkfish (Chanos chanos Forskal) and prawn (Penaeus monodon Fabricius) in polyculture in brackishwater ponds

Abstract

Milkfish (Chanos chanos) and prawn (Penaeus monodon) were stocked in 500 m2 earthen ponds from 12 November 1978 to 15 March 1979 at the following combinations: 2000 milkfish fingerlings per ha (treatment I); 2000 milkfish fingerlings plus 4000 prawn juveniles per ha (treatment II); and 2000 milkfish fingerlings plus 8000 prawn juveniles per ha (treatment III), with three replicates per treatment.

Highest combined net milkfish and prawn production was obtained in treatment III with 492.1 kg/ha followed by treatment II with 404.1 kg/ha, and treatment I (milkfish only) with 280 kg/ha. Differences in combined net production between treatments III and I and between treatments II and I were statistically significant at the 5% level. Average net production of milkfish alone was also highest in treatment III followed by treatment II and treatment I, although differences were not significant. Average net production for prawn was also better in treatment III than in treatment II but the difference was not significant. However, mean weight of prawn was higher in treatment II compared to treatment III. Average survival rates were high for milkfish in all treatments ranging from 90 to 96%, but low for prawn at around 50% for both treatments. There was no significant difference in survival rates of milkfish among treatments and of prawn between treatments II and III. The competition index between milkfish and prawn at the given stocking combinations was negative indicating a positive, advantageous influence of prawn on milkfish production.