Farm trials
Following the CTU pond trial experiment, we wanted to demonstrate
the effectiveness of these diets on commercial snakehead
farms. The C. striata farm trial experiment was carried out at two
farms inAn Giang and Dong Thap provinces simultaneously.At each
farm the test was set up with 6 hapas (50 m2/hapa) with a stocking
density of 100 fingerlings/m2. Hapas were placed in 2 ponds, each
500 m2. In pond 1, snakehead fingerlings (12–13 g/fish) in the three
hapas were fed marine trash fish (control treatment) for 6 months.
In pond 2, snakehead fingerlings (12–13 g/fish) in the three 3 hapas
were fed formulated feed. During the first two months, snakehead
fingerlings were fed a diet named CTU-CRSP 1 with 44% crude protein
(CP). In the third month, fish were fed diet CTU-CRSP 2 (41%CP)
and in the two last months,they were fed CTU-CRSP 3 (38% CP). The
formulation of three diets is given in Table 2.
Formulated feed was made from the main ingredients Kien
Giang fish meal, defatted soybean meal, cassava meal, and dried
rice-bran. All diets were made in an extruding pellet mill at CTU.
Trash fish was marine trash fish bought from markets and was
chopped up before feeding. In both CTU pond trials and farm trials,
the amount of feed used daily was recorded. The following
water quality parameters were measured monthly: transparency
(Secchi disk), pH, dissolved oxygen, ammonia and nitrite. Growth
was recorded monthly by weighing 30 fish/hapa. At the end of the
experiment, a sensory evaluation, described below was also conducted
to compare the fillet quality of experimental fish and wild fish.