To find out the compatibility of three penaeid shrimps, namely, Penaeus monodon, P. semisulcatus and Fenneropenaeus indicus for polyculture, and to compare their growth rates under similar environmental conditions, a preliminary polyculture trial was carried out in a 0.08 ha earthen pond by stocking their seeds at the rate of 6.25 post larvae /m2. Hatchery produced post larvae (PL 25) of P. monodon and P. semisulcatus

and wild post larvae of F. indicus were stocked at a ratio of 5:20:5 respectively. Shrimps were fed with pelleted feed No. 1- 4 which were gradually increased in quantity and size of the pellets as the shrimp grew in size. On day 70, as mortality was observed for tiger shrimp due to White Spot Syndrome Virus (WSSV)infection, all the shrimps in the culture system were harvested for observations on the infection, and to work out the rates of their survival, growth, production as well as the food conversion ratio (FCR). Production rate and FCR were found at 301 kg/ ha and 1.33 respectively. The overall survival rate was 51.22% with variations among the three species; being much higher for P. semisulcatus (69.3%) than for the other two species (<37.0 %). Growth in total length (TL) and weight (wt.) also varied significantly (P < 0.05) among the three species, P. monodon registering faster growth (114.5 mm TL/ 11.36 g. wt.) than the other two species; 101.24 mm TL/ 8.8 g wt. and 103.5 mm TL/ 8.1 g wt. for P.semisulcatus and F.indicus respectively. About 52.0% of the harvested animals of P. monodon showed clinical symptoms for WSSV infection such as presence of white spots and patches on carapace whereas none of F. indicus and P. semisulcatus exhibited any trace of such symptoms, revealing that P. monodon was more susceptible to WSSV infection.

Polyculture, Penaeus monodon, P. semisulcatus, F. indicus, WSSV infection