The diagrammatic sketch of the experimental
recirculatory system is shown in Fig. 1. Each
recirculatory system consisted of series of three
circular tanks (25 L) measuring 19 × 15.5 in.
(height×diameter) arranged in a 2-tier system having
partitions with separate water inlets and drains for
each. There was a provision for uplifting water from
large tanks (37×25×19.5 in.) fitted at the bottom for
storage to upper tank with same measurements. Both
tanks were installed at the height of 56 in. An
upliftment of water took place through a monobloc
tullu pump set (230–250 V, 2800 rpm and 0.6 A)
fitted with repeated cyclic meter. Separate tanks were
used for each of the food and three replicates were
used for each treatment. The adjustment in the
feeding ration was made as per intensity of feed
intake recorded from time to time during the
experiment. In each recirculatory system, the post
larvae were fed at 10% body weight per day during
the first week, 8% per day during the second week
and 5% per day during the third and fourth weeks
respectively. Rations were given twice daily i.e. of
the morning (10.00 h) and evening (16.00 h).
Satiations were determined based on visual observation
of acceptance and refusal of feed. The total
length (TL) of larvae stocked initially ranged from
41.11±4.9 mm to 48.8±7.04 mm with an average
size of 45.26±2.43 mm. The body weight ranged
from 0.5±0.06 g to 0.97±0.29 g with an average
weight of 0.66±0.13 g