REPRODUCTIVE BIOLOGY OF GOBIOCYPRIS RARUS

Reproductive biology of the rare minnow, Gobiacypris rarus, was studied both in the field (Liusha River, Hanyuan County, Sichuan Province) and in laboratory experiments from March 1990 to May 1991. Spawnings may occur throughout the year in the aguarium under controlled conditions (temperature, food etc.), though the breeding season in the field lasts from March to November only, when the water temperature is above 14℃. Fingerlings attain sexual maturity when they are 4 months old under favorable cultured conditions. The eggs are adherent, with transparent membrances. The diameter of the egg membrance is between 1.25 and 1.70 mm. Spawning. often begins at dusk and usually finishes before midnight. Observations on 136 spawnings by 7 pairs of rare minnows showed that the interval between successive spawnings ranged from 3 to 20 days, (usually 3 to 6 days); the mean spawning interval was 5.4 days and the mode was 4 days. The number of eggs produced per spawning ranged from 2 to 768 (average 300.3). Based on the unsynchronous development of oocytes, distribution of egg diameters, frequency of spawnings, and continuous recruitment of oocytes, the rare minnow is reguarded as a continuous batch spawner. A discussion was made on the classification of spawning patterns in fish and the potential uses of the rare minnow.