金魚の周年採卵法について

概要

論文の詳細を見る
An attempt to induce artificial spawning of goldfish at any season of the year was tried during the period ranging from April, 1965 to March, 1966. The results obtained are as follows: 1) At the end of April the two-year-old fish were collected from an outdoor pond and removed to indoor aquaria regulated at 13-14°C. They were kept in the aquaria separately by sex under the natural daylight until the end of December. In spawning experiments several females showing the ponderal index more than 0.05 were selected from the stock fish, and each fish was transferred to a spawning aquarium at about 20°C, which was supplied with some water plants for spawning nests, together with a male fish which could release a small amount of milt under a slight pressure on his belly. By this method successful spawning was observed in these fish every month from April to December. Of 47 experimental fish, 44 females spawned within ten days after they had been transferred to the experimental aquaria, two fish showed no spawning and one died. Among the spawned females 33 individuals laid eggs on the second day of the experiment. 2) From December to February, immature females were first maintained in a high temperature at about 20°C to accelerate the growth of oocytes, By this treatment maturing of the ovaries was hurried up and the fish showed a ponderal index of above 0.05 after being kept in this condition for some 30 days in December, 14 days in January, and for 8 days in February. In March some fish had already arrived at the same maturing conditions as above without any treatment. About 66 per cent of the experimental females spawned by only being removed to the similarly conditioned aquaria as above or after the treatment with HCG. 3) The injection of HCG, 30 units per lOg body weight, just before the transfer of fish to the spawning aquaria, always makes spawning reaction prompt, and 74.2 per cent of the injected fish laid eggs on the next day after the injection. 4) The amount of eggs spawned was calculated from the difference between body weight just before spawning and that just after spawning. Average weights of spawned eggs were about the same in a month, and the weight of spawned eggs as compared to body weight was 12.6 per cent in average in the treatment with high temperature alone and 10.9% in the treatment with both HCG and high temperature. 5) Average fertilization rates all through the experimental period were 78.7 per cent in the high temperature experiments and 77.5 per cent in both HCG and high temperature treatments, and hatching rates were 68.4 and 66.2 per cent on the average respectively. 6) The male fish maintained their full maturity all through the year by being kept in an aquarium at 13-14°C and they could release plenty of sperm within a day due to their removal to the spawning aquaria at about 20°C.

金魚の周年採卵法について

スポンサーリンク

概要

著者

関連論文

スポンサーリンク