Abstract
The following are some results obtained from a series of experiments in rotifer culture and its usage for the food of tiny fish fry: 1, Outdoor concrete ponds, each being $16m^2$, were used to culture the rotifers, Brachionus calyciflorus, and Filinia longiseta. Brachionus calyciflorus usually attained the population of about 100 individuals per ml of pond water. Dipterex was usually applied to control Daphni,a and other crustaceans that generally appear and feed on rotifers. A concentration of 0.16 to 0.2 ppm in the pond water was sufficiently effective to control these natural enimies of rotifers. Poultry dung was very effectively used to multiplicate rotifers. The fertilization ratio was about 8 kg each pond with 30cm depth of water. 2. The tiny rotifer, Filinia longiseta attained a very high population density of about 1,000 individuals per ml of pond water, but they were very sensitive to dipterex, and for this aspect future investigation may be needed. 3. In the outdoor ponds, the multiplication of rotifers significantly decreased when the water temperature falls to about $20^{\circ}C$ in autumn. 4. In the laboratory room, unicellular planktonic algae such as Scenedesmus or Chlorella, as the food of rotifers, were collected from the outdoor ponds by dipping them together with water, and were effectively used for the culture of Brachionus calyciflorus. If the planktonic algae are cultured in specially designed containers, the sun-light would be the most effective means as the source of light. 5. Brachionus calyciflorus cultured in the outdoor ponds by the dipterex controlled method was highly efficient to rear the early fry of marble gourami. The dipterex content mixed in the water to control the crustacean emmies of rotifers sieved no harm to the gourami fish fry.
1. Brachionus calyciflorus의 실외 시비 배양에서 $16m^2$의 콘크리이트 못에서 1ml당 약 100개체의 고밀도 배양이 가능하였으며, 발생 시작 후 $2\~3$일 째에 dipterex를 $0.16\~0.2ppm$유효 성분 농도로 살포하여 Daphnia등 다른 갑각류의 발생을 억제함으로써 약 2주일 동안 그 발생 상태를 유지할 수 있었다. 이 때 사용된 비료는 닭똥이 약 8kg이며, 수심은 30cm 전후로 하였다. 2. 수온 $20^{\circ}C$ 이하로 내려가면 그 발생이 극도로 저하한다. 3. Filinia longiseta등 소형 rotifer는 1ml당 약 1000개체의 고 밀도로 발생이 가능하나 dipterex에 대하여 대단히 약하며 앞으로 상세한 실험이 요청된다. 4. 실내에서 Brachionus calyciflorus를 배양할 때는 그 먹이인 녹조류를 실외의 못에서 배양하거나 또는 태양광선을 이용할 수 있는 장치를 실내에 하는 것이 좋다고 인정된다. 5. marble gourami의 어린 자어에 Brachionus calyciflorus를 먹이니 그 성장이 잘 되었다. 이 때 dipterex를 사용하여 다른 갑각류를 억제하면서 발생시킨 것을 바로 먹여서 자어에게 아무런 지장을 초래하지 않았다.