The brown trout is an economically important species, particularly due to its popularity with anglers, and stocks are maintained in many areas by artificial introductions (2).
This fish feeds on invertebrates, insect larvae, aerial insects, and molluscs, as well as the occasional fish and frog (4). Spawning occurs between January and March, when females are accompanied by a number of males. The eggs, which are fertilised externally, are covered with gravel by the female. For the first days after hatching, the young fish (fry) derive their nutrients from their large yolk sacs; they then feed on small arthropods, such as insect larvae (2). The maximum-recorded life span of a brown trout is 5 years (4).