We evaluated the potential of the euryhaline copepod Pseudodiaptomus inopinus as a prey to enhance the feeding activity of red sea bream Pagrus major larvae. Pseudodiaptomus inopinus was used to evaluate free amino acid composition and dietary effects on the rearing performance of fish larvae, in comparison to rotifers (control prey). Among free amino acids, alanine, arginine, and glycine were markedly higher in P. inopinus than in rotifers. Larvae were reared for 20 days post-hatching under three feeding treatments: rotifers (control), rotifers supplemented with copepods, and copepods only. Larvae fed copepods alone had a higher growth rate than those in the other treatments. However, the survival rates of these larvae were lower than those under control or copepod supplementation. While equivalent stocking densities of rotifers were employed in the rearing water for both larvae, whether supplemented with copepods or not, the supplemented treatment yielded diminished larval survival and failed to enhance growth rates. According to gut content analysis, larvae receiving supplemented treatment preferentially fed on copepods, and the number of ingested rotifers was reduced. As a result, total ingested mass was lower in the supplemented larvae. This study suggests that copepods containing free amino acid species negatively affect prey acceptance of fish larvae.

我们评估了广盐桡足类Pseudodiaptomus inopinus作为猎物增强红真鲷幼虫摄食活动的潜力。与轮虫（对照猎物）相比，使用Pseudodiaptomus inopinus来评估游离氨基酸组成和饮食对鱼类幼虫饲养性能的影响。游离氨基酸中，丙氨酸、精氨酸和甘氨酸在P. inopinus中明显高于轮虫。幼虫在孵化后在三种喂养处理下饲养20天：轮虫（对照）、补充有桡足类的轮虫和仅桡足类。单独喂养桡足类的幼虫比其他处理中的幼虫具有更高的生长率。然而，这些幼虫的存活率低于对照或桡足类补充剂的幼虫。虽然在两种幼虫的饲养水中采用了相同的轮虫放养密度，但无论是否补充桡足类，补充处理都会降低幼虫的存活率，并且无法提高生长速度。根据肠道内容物分析，接受补充处理的幼虫优先以桡足类为食，摄入轮虫的数量减少。结果，补充的幼虫的总摄入量较低。这项研究表明，含有游离氨基酸的桡足类动物会对鱼类幼虫的猎物接受度产生负面影响。