Effect of different water exchange on initial
feeding incidence of D3-D10 old larvae of humpback grouper (GRIMC)
The rearing of humpback grouper larvae was conducted
in 9 polycarbonate tanks, 200 litre volume, and filled with sea water with
the salinity of 34 ppt. Ten fertilized eggs per liter were stocked in each
tank. Started at day-3, the larvae were fed SS-type rotifers with the
density of 5 ind/ml.
During the D-3 to D-10 rearing period, larvae were
reared at different water exchange as treatment in, i.e. A: without water
exchange, B: 100 % water exchange, and C: 200 % water exchange. Three
replicates were set for each treatment. Development of larvae in each tank
was observed every day. Stomach content and total length of larvae were
observed every two days.
Results of the experiment showed that growth of humpback
grouper larvae in all treatments was not significant different
(P>0.05). Total length of the larvae in treatments A, B, and C were 3.72
± 0.08, 3.60 ± 0.10, and 3.57 ± 0.18 mm, respectively. Survival rate of
larvae at day-10 for treatment A, B, and C were 38.1 ± 12.7, 24.8 ± 8.3,
and 20.2 ± 8.3 %, but these survival values of larvae were not significant
different (P<0.05). The number of rotifers in the gut of larvae during
the day-3 to day-8 rearing period were 1.8-20.2, 1.8-13.2, and 1.8-15
individuals for treatment A, B, and C, respectively.
(from Grouper Research Briefs in Aquaculture Asia,
Vol. VI, No. 2, April-June 2001)