Table_1_Tracing the journey of elements from fish feed to Nile tilapia faeces to black soldier fly larvae: a comparative approach.DOCX

IntroductionThe circular bioeconomy concept revolves around biological production cycles that reintroduce products or waste from one production system to another, aiming to maximize resource utilization while minimising environmental impact. The purpose of this study was to evaluate and compare the element flow when integrating black soldier fly larvae (BSF) production with Nile tilapia production using varying experimental fish feed.
MethodsTilapia (42.5  ± 11.2  g) were reared in recirculating aquaculture systems (RAS) at 25.5°C for 10  weeks and fed equal daily rations of four experimental diets containing fishmeal (FM), poultry blood meal (PBM), black soldier fly meal (BSF) and poultry by-product meal (PM) as the single main protein source, respectively. Faeces was collected daily from settling columns installed in the RAS and subsequently fed to BSF larvae.
Results and discussionThe fish exhibited the highest biomass gain when fed with FM (1,001  g) or PM (901  g). The growth was lowest for those fed with PBM (406  g). The fish fed with PBM also produced the highest amount of faeces (234 g). When the fish faeces were utilized as a substrate for rearing black soldier fly (BSF) larvae and although the biomass gain did not differ significantly, the feed conversion ratio (FCR) varied among larvae fed with different fish faeces, ranging from 8.36 to 25.04. Furthermore, the concentration of analysed elements (Al, B, Ca, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, S, and Zn) varied based on the type of fish faeces provided. Results illustrate that a modulation of BSFL elemental composition is possible through manipulating the feed provided to the fish and emphasize the importance of fish feed composition for fish performance as well as the compositional quality of the larvae reared on the resulting fish faeces. Hence, if BSF larvae production is to be harnessed for the recycling of aquaculture sludge, ingredient choice and subsequent elemental composition of fish feeds are pivotal to larvae composition.

引言
循环生物经济（circular bioeconomy）的核心围绕生物生产循环展开，即将某一生产系统的产品或废弃物重新引入另一生产系统，旨在最大化资源利用率并最小化环境影响。本研究旨在评估并对比：将黑水虻幼虫（black soldier fly larvae, BSF）养殖与尼罗罗非鱼养殖相结合时，使用不同实验鱼饲料的元素流动情况。

方法
选取初始体重为42.5±11.2 g的罗非鱼，在25.5℃的循环水产养殖系统（recirculating aquaculture systems, RAS）中饲养10周，每日投喂等量的四种实验饲料，四种饲料分别以鱼粉（fishmeal, FM）、家禽血粉（poultry blood meal, PBM）、黑水虻粉（black soldier fly meal, BSF）和家禽副产物粉（poultry by-product meal, PM）作为单一主要蛋白质源。每日从循环水产养殖系统的沉降柱收集鱼粪便，随后将其作为底物饲喂黑水虻幼虫。

结果与讨论
投喂鱼粉（生物量增益达1001 g）或家禽副产物粉（生物量增益达901 g）的罗非鱼表现出最高的生物量增益，投喂家禽血粉的罗非鱼生物量增益最低（406 g）。投喂家禽血粉的罗非鱼产生的粪便量最高（234 g）。以鱼粪便作为底物养殖黑水虻幼虫时，尽管幼虫的生物量增益无显著差异，但投喂不同鱼粪便的幼虫的饲料转化率（feed conversion ratio, FCR）存在差异，范围为8.36至25.04。此外，分析的元素（铝Al、硼B、钙Ca、钴Co、铜Cu、铁Fe、钾K、镁Mg、锰Mn、钼Mo、钠Na、磷P、硫S和锌Zn）的浓度因投喂的鱼粪便类型不同而存在差异。研究结果显示，通过调控鱼类饲料的组成可调节黑水虻幼虫的元素组成，同时强调了鱼饲料组成对鱼类生长性能以及以该鱼粪便养殖的幼虫的组成质量的重要性。因此，若要利用黑水虻幼虫养殖回收水产养殖污泥，鱼饲料的原料选择及其后续的元素组成对幼虫的组成至关重要。