POTENTIAL FOR POLYCULTURE OF TILAPIA Oreochromis nilotius AND FRESHWATER PERCH Anabas testudineus WITH PANGASIUS CATFISH Pangasius hypopthalamus IN THE HYPOSALINE WATERS OF SOUTHERN BANGLADESH

Pangasius catfish (Pangasius hypopthalamus), tilapia (Oreochromis niloticus), and freshwater perch (Anabas testudineus; locally known as Koi) are three of the most successful freshwater aquaculture species in Bangladesh. We previously established that Pangasius can be cultured in hyposaline waters, allowing for use of coastal waters affected by salinity encroachment. In the present study, we assessed the potential for culturing Pangasius with the higher valued tilapia and freshwater Koi in hyposaline waters of coastal Bangladesh as a means of improving the food security and economic viability of these salinity affected region's poor communities. The experiment was conducted in 16 farmer's ponds in the Patuakhali district of Bangladesh at a salinity of 5-6 ppt. Four culture types were examined (Table 1) with fish being fed commercial pellet feed (CP 28-30%) twice daily at a total rate of 10% down to 3% body weight per day.

The study revealed that Koi can be cultured in saline waters as high as 6 ppt and that the highest yields could be obtained through solo culture of Pangasius (T1). However, due to the higher market value of tilapia and greater increases in body weight of both Pangasius and tilapia, the largest profit came from the co-culture of these two species (T2).  This was followed by co-culture of Pangasius with Koi (T3).  Conversely, the lowest yield and profit resulted from the culture of all three species together (T4). Thus, the results suggest that tilapia is the optimal candidate for polyculture with Pangasius in hyposaline waters with a Koi polyculture providing the second greatest profit margin. Adoption of such aquaculture practices in coastal Bangladesh could increase earnings and improve the livelihoods of the people inhabiting these areas.

(Supported by the AquaFish Innovation Lab - USAID)