The experiment involved three ranges of water temperature: 11-13; 15-16; and 18-20°C, applied during incubation of eggs produced by pond-reared ide spawners. Each temperature range was maintained in 5 tanks, each holding 100 fertilised eggs the survival rate of which was being assessed. Throughout the experiment, the incubated eggs were examined and the timing of the onset and termination of hatching was determined. Once the larvae hatched, their total length as well as the length, height, and volume of the yolk sac were measured. The highest egg surival rate (64.6%) occurred at the lowest incubation temperature range (11-13°C), a somewhat lower survival (59.2%) being recorded at 15-16°C. The lowest survival rate (about 40.6%) was typical of the highest incubation temperature range. The duration of egg incubation and embryonic development of the ide was found to be related to water temperature. The 11-13°C range delayed the onset of hatching and prolonged its duration. Incubation at 18-20°C was found to accelerate the embryonic development and was decisive for the earliest onset of hatching and its shortest duration. The longest larvae (6.25 mm total length) were those hatched from eggs incubated at 15-16°C. Those larvae hatched from eggs incubated at 11-13°C were shorter (averaging 6.06 mm total body length). The smallest larvae (5.81 mm total body length) were those hatched from eggs incubated at 18-20°C. The size of the yolk sac in the newly hatched larvae was dependent on water temperature prevailing during the embryonic development. Yolk sacs of the larvae hatched from eggs incubated at 11-13 and 15-16°C were larger than those of the larvae hatched from eggs incubated at the highest temperature range (18-20°C).

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