Freshwater fish in zoo aquarium exhibits are often an afterthought in welfare discussions, but they have complex needs that can be well-met or poorly met depending on exhibit design and management quality.
Freshwater fish welfare in zoo aquariums sits at a welfare frontier where growing scientific evidence of fish sentience meets variable institutional knowledge and resources. A well-designed freshwater exhibit with appropriate species grouping, water quality, enrichment through habitat complexity, and appropriate nutrition can provide good welfare for fish. A poorly designed exhibit - wrong water parameters, incompatible species, inadequate schooling group size, or barren environment - imposes chronic welfare costs on animals who cannot be relocated by their own choice. Zoo accreditation increasingly addresses aquatic animal welfare, but specific fish welfare expertise and species-appropriate standards remain less developed than for mammals and birds.