Description and quantification of mortality in red tilapia (Oreochromis niloticus) cultured in close proximity to Pangasius (Pangasius hypophthalmus) aquaculture systems in the Mekong Delta, Vietnam

Principal Investigators: Jeff Davidson, Larry Hammell & Annette Boerlage (UPEI) Co-Investigators: Dr. Tu Thanh Dung & Dr. Tran Thi Tuyet Hoa (Can Tho University, Vietnam)

Describing mortality of red tilapia in floating cage aquaculture in the Mekong Delta, Vietnam

Vietnam has one of the most productive aquaculture industries in the world, and produces 80% of its fish in the Mekong Delta. Red tilapia is a recently cultured species in the Mekong Delta that has become important for local consumption. We investigated basic production variables for associations with mortality, and described red tilapia aquaculture in small-scale, floating-cage farms in the Mekong Delta. Most farmers never record information about stocking, harvesting, or mortalities. Farms are relatively small, about 4 cages per farm, and cages are 10 x 5 x 3.5 meters in size. We used a questionnaire, sampled fish, and asked farmers to record daily mortality during one production cycle.

Questionnaire results showed that it takes 5-6 months to grow red tilapia to harvest size. Farmers estimate that mortality between stocking and harvesting is 20 to 30%. Daily mortality records showed that mortalities decreased during the cycle for most farms, with considerable day-to-day variation.

Farmers often sell dead fish as food to catfish farms, and we sampled them for parasites and clinical signs, and found that 5 – 6 % were infected with two common bacteria, Streptococcus agalactiae and Aeromonas hydrophyla. This is the first study to quantify mortality related factors in red tilapia aquaculture.