New and viable species for aquaponics and integrated multi‐trophic aquaculture (IMTA) in freshwater systems can improve yields and sustainability of aquaculture. Freshwater crayfish species such as Astacus astacus and Pontastacus leptodactylus are omnivorous feeders and considered candidates for feeding on faecal matters in existing aquaculture systems. Feeding trials were conducted to determine growth response and RNA/DNA ratio in freshwater crayfish fed fish waste. Carapace length and wet weight were measured to determine the growth response. Juvenile A. astacus was fed faeces of hybrid striped bass (Morone chrysops × Morone saxatilis) and rainbow trout (Oncorhynchus mykiss), while adult P. leptodactylus was fed with two commercial pellet diets and pikeperch (Sander lucioperca) faeces. The nutritional composition of hybrid striped bass faeces was close to optimal diet composition of A. astacus, and crayfish showed significantly higher carapace growth, weight gain and weight gain per moult as the group fed rainbow trout faeces. The growth of P. leptodactylus was significantly lower in terms of weight gain and weight gain percentage per moult for crayfish fed on pikeperch faeces. Thus, this study can recommend a co‐cultivation of hybrid striped bass and A. astacus within one system, but cannot recommend co‐cultivation of P. leptodactylus with pikeperch. Additionally, this study showed controversial results of RNA/DNA ratio and weight gain of both crayfish species. Thus, RNA/DNA ratio cannot be approved for investigations on crayfish physiological status in controlled feeding experiments if animals are fed with an inadequate diet.

中文翻译：

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饲喂鱼废饲料的贵族小龙虾（Astacus astacus）和窄爪小龙虾（Pontastacus leptodactylus）的生长性能和RNA / DNA比

淡水系统中用于水培和综合多营养水产养殖（IMTA）的新的可行物种可以提高水产养殖的产量和可持续性。淡水小龙虾（例如Astacus astacus和Pontastacus leptodactylus）是杂食性饲养者，被认为是现有水产养殖系统中以粪便为食的候选动物。进行了饲喂试验，以确定淡水小龙虾饲喂鱼粪的生长反应和RNA / DNA比率。测量甲壳的长度和湿重以确定生长响应。少年A. astacus被喂食混合条纹鲈鱼（Morone chrysops  ×  Morone saxatilis）和虹鳟（Oncorhynchus mykiss）的粪便。），而给成年的P. leptodactylus喂食两种商业颗粒饲料和鲈鱼（Sander lucioperca）的粪便。杂交条纹低音粪便的营养组合物接近的最佳饮食组合物A.螯和小龙虾表明每换羽显著更高甲壳生长，增加体重和体重增加为组饲喂虹鳟鱼粪便。就以梭鲈粪便为食的小龙虾的体重增加和每只换羽的体重增加百分比而言，P。leptodactylus的生长明显较低。因此，本研究可以建议在一个系统中将条纹鲈鱼和紫茎泽兰混合培养，但是不能建议对P. leptodactylus进行共培养。和长矛。此外，这项研究显示了两种小龙虾的RNA / DNA比例和体重增加的争议结果。因此，如果动物饲喂的饮食不足，则不能批准RNA / DNA比值用于控制饲喂实验中的小龙虾生理状况调查。