2.6. Diet preparation and feeding
The feed was produced by careful mixing of the dry ingredients
before adding squid oil and distilled water. The amount of distilled
waterwas adjusted to get the mixture to forma stiff dough. The pelleted
feed wasmade using an electronic meat grinder (Quoc Hung company,
Vietnam), with diameter and length of pelleted feed in the range of
1–2 mm. All diets were sun-dried for two to three days, and then
weighed and stored in sealed plastic bags in small portions at 5 °C until
use. New batches of experimental feeds were made bi-weekly. The fish
were fed by hand to apparent satiety with about 3–5% of body weight
per day at 9.00 h and 14.00 h and uneaten feed was collected after
feeding using a fish racket for floating material and by opening the valve
at the bottom of the sediment collection tube of each tank to flush out
sedimented feed material.