Studies on the Availability of Heterotrophic Flagellates and Ciliates as Prey Organisms for Reared Fish Larvae

褶皱臂尾轮虫（Brachionusplicatilisrotundiformis）是水产养殖中广泛使用的饵料生物，但由于体型过大，导致早期死亡率较高。本研究旨在探讨小型原生浮游动物鞭毛虫和纤毛虫作为仔稚鱼替代饵料的可行性，并采用微生物学方法对天然仔稚鱼肠道内容物进行了观察。取幼虫消化道，荧光素、FITC和DAPI染色，在荧光显微镜下观察。结果表明，319只个体中的47只中，约有20个属显然捕食了许多大小为10至40 μ m的原生动物生物，其中有几种鞭毛虫和纤毛虫以真鲷、比目鱼、棘舌鱼和赤石斑鱼的幼鱼为食。结果表明，2日龄的赤点石斑鱼（E.akaara）和6日龄的真鲷（P.major）仔鱼均以纤毛虫为食，表明纤毛虫等小型原生浮游动物是口部较小的幼鱼理想的饵料。

The S-type rotifers, Brachionus plicatilis rotundiformis, widely used as prey organisms for fish larvae in aquaculture are often too large for a gape size of some fish species to take up, resulting in the high mortality in early stages. This study aimed the availability of protozoan microzooplankton of flagellates and ciliates for an alternative food of fish larvae.Preliminarily, gut contents of natural fish larvae were observed by using microbiological method. Digestive tracts of larvae were removed, stained by fluorescein dye, FITC and DAPI, and were observed under epifluorescence microscopy. It was clarified that some 20 genus, out of 47 among 319 individuals, apparently foraged many protozoan organisms with a size of 10 to 40 mum.A couple of stains of flagellate and ciliate were fed on young larvae of Pagrus major, Paralichthys olivaceus, Plecoglossus altivelis, and Epinephelus akaara. Results obtained showed that larvae of E.akaara of 2 day-old and P.major of 6 day-old consumed ciliates.These results indicate that protozoan microzooplankton such as ciliates are promising food for fish larvae with relatively small mouth in aquaculture.