According to the Online Aulete dictionary, ichthyofauna is the group of fish that live in a certain environment, or even the group of fish species that exist in a given biogeographic region.

In Brazil, ichthyofauna comprises approximately 2,300 freshwater species (number compiled from the Check List of the Freshwater Fishes of South and Central America, REIS et al., 2003), which is mainly due to the presence of several large hydrographic systems, with considerable ichthyofaunistic distinction between them.

The monitoring of ichthyofauna occurs mainly for two reasons: the first, it is carried out by universities and researchers, which have the objective of cataloging new species and/or studying the behavior and ecology of known species. The second is the monitoring of the ichthyofauna, which can be harmed by anthropogenic changes in aquatic environments.

The main problems of loss of ictic diversity related to anthropogenic changes in aquatic environments are those directly or indirectly related to pollution (chemical and organic), deforestation (transformation of native vegetation into planting and pasture areas), construction of dams (alteration of lotic and lentic environments), predatory fishing and introduction of species (alien or exotic).

A worrying aspect from the point of view of the conservation of this biodiversity is the lack of information on the ecology, biology and systematics of most of these taxa, hindering more accurate analyzes and assessments of impacts arising from anthropogenic changes in aquatic ecosystems in recent decades.

It should be noted that the two main reasons for monitoring fish complement each other. It is necessary that studies are developed, so we can know the behavior and ecology of the fauna. And only then we be can able to diagnose, through monitoring, whether anthropogenic changes in aquatic environments are negatively influencing the characteristics of fish fauna in a given geographic region.

Therefore, the study and monitoring of the ichthyofauna is extremely important as it allows a diagnosis of fauna conditions to be established in the places of anthropic changes, in addition to predicting and mitigating possible impacts on the fishing community.

Zenon Ratzlaff