Morning (06:30 h) and afternoon (15:30 h) temperatures
and dissolved oxygen concentrations were monitored with a
DO meter (YSI model 58) once a week. Ammonia-N and
nitrite-N concentrations were analyzed at the beginning, middle
and end of the experiment by collecting and mixing 300 mL of
water from each replicate tank of the same treatment in a 1-litre
plastic bottle. Samples were duplicated for each treatment and
analyzed by using spectrophotometric method for ammonia–
nitrogen (standard Phenate method) and nitrite–nitrogen