To estimate the number of eggs, place
all eggs in a bucket with known volume,
e.g. 10L. Stir the water gently to disperse
the eggs in the water column. Take five
1-ml subsample, then count number
of eggs in each subsample using the
Sedgewick-Rafter chamber under a
compound microscope. Get the average
of the 5 subsamples and multiply with the
total volume of the water in the container.
Estimate also the fertilization rate by
dividing the number of fertilized eggs by
the total number of eggs counted.
Eggs are stocked in the hatching-cumlarval
rearing tanks at a stocking density
of 0.5-1 per ml for incubation, hatching and
subsequent rearing the newly-hatched
larvae. Hatching occurs at 36 hrs after
fertilization at water temperature of 25-29
oC (Fig. 7).
14