Ponds at both sites were managed similarly using a multi-batch
production system and the same stocking density of fingerlings
(14,820 fish ha−1) and carryover fish (2280 kg ha−1). Carrryover
fish are those weighing more than 350 g that were stocked the previous
year but are not yet market size. Fish were stocked into five
replicate 0.04-ha ponds that were randomly assigned to each diet at
NWAC, and five replicate 0.10-ha ponds were randomly assigned to
each diet at UAPB. Ponds were maintained as static systems; water
loss due to evaporation and seepage was replenished. Total ammonia–
nitrogen (TAN), nitrite–nitrogen (NO2–N), and pH were measured biweekly
for the duration of the growing season at approximately 1300
to 1600 h using a field kit (Hach Chemical, Loveland, Colorado) and
maintained in ranges considered adequate for optimum fish performance
(Tucker and Robinson, 1990). Chloride concentration was
maintained at ≥100 mg/L to alleviate possible nitrite toxicity.