Ichthyofauna

Ichthyofauna refers to the fish fauna of a region, ecosystem, or water body. The term encompasses all species of fish that occur there, spanning major lineages such as jawless fish (cyclostomes), cartilaginous fish (sharks, rays, and chimaeras), and bony fishes (osteichthyans). Ichthyofaunal assemblages are shaped by salinity, depth, temperature, substrate, and productivity, and they differ markedly between freshwater and marine environments as well as among biogeographic regions.

Assessments are conducted through field surveys, netting, trapping, electrofishing, visual surveys, and increasingly environmental DNA (eDNA). Metrics such as species richness, Shannon diversity, evenness, and relative abundance spectra describe assemblages and guide conservation and management decisions.

Many species are migratory; diadromy (anadromy and catadromy) links freshwater and marine systems and influences distribution patterns. Endemism can be high in isolated or ancient basins, while some regions host cosmopolitan assemblages.

Threats to ichthyofauna include overfishing, habitat destruction, pollution, invasive species, and climate change, all of which can reduce diversity and alter community structure. Management responses include protected areas, sustainable fisheries, habitat restoration, pollution control, and hydrological planning to maintain connectivity and water quality.

Ichthyofauna is central to ecosystem structure as predator, prey, and contributor to energy transfer, and it supports human livelihoods through fisheries and aquaculture. As a biodiversity indicator and resource, studies of ichthyofauna inform biodiversity assessments, ecological research, and environmental monitoring.