The aquaponic principle is the coupling of animal aquaculture (e.g. fish) with plant production (e.g. vegetables) for saving resources. At present, various definitions of aquaponics exist, some bearing the risk of misinterpretation by dismissing the original meaning or being contradictory. In addition, there is no standard terminology for the aspects of coupling between the aquaponic subsystems. In this study, we addressed both issues. (1) We developed new or revised definitions that are summarised by: Aquaponic farming comprises aquaponics (which couples tank-based animal aquaculture with hydroponics) and trans-aquaponics, which extends aquaponics to tankless aquaculture as well as non-hydroponics plant cultivation methods. Within our conceptual system, the term aquaponics corresponds to the definitions of FAO and EU. (2) A system analysis approach was utilised to explore different aquaponic setups aiming to better describe the way aquaponic subsystems are connected. We introduced the new terms ‘coupling type’ and ‘coupling degree’, where the former qualitatively characterises the water-mediated connections of aquaponic subsystems. A system with on-demand nutrient water supply for the independent operating plant cultivation is an ‘on-demand coupled system’ and we propose to deprecate the counterintuitive term ‘decoupled system’ for this coupling type. The coupling degree comprises a set of parameters to quantitatively determine the coupling's efficiency of internal streams, for example, water and nutrients. This new framework forms a basis for improved communication, provides a uniform metric for comparing aquaponic facilities, and offers criteria for facility optimisation. In future system descriptions, it will simplify evaluation of the coupling's contribution to sustainability of aquaponics.

中文翻译：

---

鱼菜共生原理——一切都与耦合有关

鱼菜共生原则是将动物水产养殖（如鱼类）与植物生产（如蔬菜）相结合，以节约资源。目前，鱼菜共生的定义多种多样，有些可能会因否定原意或自相矛盾而产生误解。此外，鱼菜系统子系统之间的耦合方面没有标准术语。在这项研究中，我们解决了这两个问题。(1) 我们制定了新的或修订的定义，概括如下： 鱼菜共生包括鱼菜共生（将基于水箱的动物水产养殖与水培相结合）和跨鱼菜共生，将鱼菜共生扩展到无水产养殖以及非水培植物栽培方法。在我们的概念系统中，鱼菜共生一词对应于粮农组织和欧盟的定义。(2) 利用系统分析方法探索不同的鱼菜系统设置，旨在更好地描述鱼菜系统子系统的连接方式。我们引入了新术语“耦合类型”和“耦合度”，前者定性地描述了鱼菜系统子系统的水介导连接。为独立运营的植物种植提供按需营养水供应的系统是“按需耦合系统”，我们建议弃用这种耦合类型的违反直觉的术语“解耦系统”。耦合度包括一组参数，用于定量确定内部流（例如水和养分）的耦合效率。这个新框架为改善沟通奠定了基础，为比较鱼菜共生设施提供了统一的衡量标准，并提供设施优化标准。在未来的系统描述中，它将简化对耦合对鱼菜共生可持续性贡献的评估。