ABSTRACT: Wild-living populations of the crucian carp Carassius carassius, a cyprinid fish of European freshwaters, have decreased in recent years, likely due to increasing competition presented by invasive species. Several initiatives have been launched in an attempt to reintroduce this fish back into its natural habitat, but these approaches require the use of crucian carp fry reared under controlled conditions, and the use of popular and inexpensive commercial diets has been found to result in developmental abnormalities. The aim of the current study was to analyse the impact of feeding juvenile crucian carp either natural food (Chironomidae sp. larvae) or 2 commercial diets, with a focus on the intestinal development of these fish. Histological analysis revealed significant pathologies in the alimentary tracts of fish fed both commercial diets; these included lowered hepatocyte and enterocyte proliferation, as well as shortened intestinal folds. Furthermore, the digestive enzyme activity patterns suggested a physiological state close to malnutrition. This study confirmed that basic commercial diets (at least the 2 applied) are not recommended for the rearing of crucian carp juveniles, even though initial growth rates of the fish might suggest otherwise.

中文翻译：

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商业饮食喂养对cru鱼cru发育的影响：消化道异常

摘要：近年来，欧洲淡水的pr鱼fish鱼Car的野生生物种群减少，这可能是由于入侵物种带来的竞争加剧所致。为了将这种鱼重新带回其自然栖息地，已经采取了一些举措，但是这些方法需要使用在受控条件下饲养的cru鱼苗，并且发现使用流行且廉价的商业饮食会导致发育异常。本研究的目的是分析饲喂幼年cru鱼或天然食品（Chi科）的影响。sp。幼虫）或2种商业饮食，重点是这些鱼的肠道发育。组织学分析表明，两种商业饮食喂养的鱼的消化道都有明显的病态。这些包括降低的肝细胞和肠上皮细胞增殖，以及缩短的肠褶皱。此外，消化酶活性模式表明接近营养不良的生理状态。这项研究证实，不建议使用基本的商业饮食（至少使用2种）来饲养cru鱼，尽管鱼的初始生长速度可能表明并非如此。