Abstract: Eggs of common carp were naturally fertilized and incubated at different temperatures 20,24,27,35 and
38°C for a period of 70 h of fertilization The present results indicated that the optimum percent of healthy eggs
was 77% at temperature of 27°C, followed by 59% at temperature of 30C°. However, no eggs were survived to
hatch at neither 20°C nor 38°C. The hatching rate at 27°C and 30°C increased than the other treated groups. The
lengths of newly hatching larvae were 3.3±0.015 mm at 24°C and yolk volume ranged from 0.421±0.005 to
0.676±0.005μl. It likely seems that, the yolk volume of newly hatching larvae varied inversely with increasing
of water temperature. The growth of larvae increased at the optimum temperature from 27-30°C. Meanwhile,
the effect of temperature ranges on the ontogeny of mucous cells showed that the optimum temperature from
24-30°C increased number and density of mucous cells in both of body surface and the alimentary canal.
Early life stage larvae (20 h-old) exposed to 24°C showed neutral mucous substance in the buccal cavity then
changed to acid mucous substance after three days post hatching. In skin of larvae (14-day old) exposed to
27°C, both neutral and acid mucous substances are located at the epidermal layer of skin. The goblet cells of
larvae (21-days old) treated with 27°C are composed of acid mucous substance which increased in number and
size towards the posterior intestine. It can be concluded the temperature has an important effect on hatching,
growth, protective role of mucin secretion in common carp and may be applied to improve carp larvae rearing
at hatchery system.
Key words:Temperature Fertilization Hatching Survival rate Histochemical examination Cyprinus
carpio