Sharma, J.G., Chakrabarti, R.
Abstract:
Grass carp with an average weight of 15 +/- 0.02 mg were reared for
35 days in rectangular glass aquaria in a recirculated water system at
four stocking densities of 200, 400, 800 and 1600/m^3 and they were
supplied with live zooplankton the amount of which increased in a
two-fold manner, starting from 4 mg (dry weight). After 20 days of
culturing the amount of feed was doubled. Though the percent of
survival was maximum and minimum in basic and eight-fold
treatments, the total number of survival showed the opposite trend.
The average weight differences were significant (P < 0.05) between
basic (65.67 +/- 2.02 mg) and either two-fold (59.67 +/- 0.32 mg) or
four-fold (56.33 +/- 0.67 mg) or eight-fold (44.33 +/- 1.20 mg), but
not between two-fold and four-fold system. The ammonia level was
maximal in eight-fold treatment followed by four-fold, two-foId and
basic systems, whereas, dissolved oxygen level showed the opposite
trend. Considering overall survival and growth performance together,
four-fold system appeared better than others.
(Department of Zoology, University of Delhi, Delhi-110007, India)