2025Croatian Fauna - Freshwater Fish (C) - Set

The brown trout (Salmo trutta) (Linnaeus, 1758) lives in rivers and streams of the Danube and Adriatic basins, as well as in lakes in its lake-dwelling form. The lake trout is considered a form that developed under the influence of a specific type of habitat and is regarded as a single species. The body is elongated and spindle-shaped, covered with small, round scales. The mouth is large, and the teeth are well-developed. Its back has black spots with white edges, while its sides feature red spots outlined in white or light blue. The body coloration is variable and depends on environmental conditions. It most commonly inhabits fast, cold and shallow mountain streams with temperatures ranging from 2 to 16°C. It typically grows up to 50 centimeters and rarely reaches 70 cm, while the lake-dwelling form can grow to an impressive 140 centimeters and weigh over 20 kilograms. The maximum recorded age is 38 years. It feeds on various animals: aquatic invertebrates, small fish, insects that fall on the water, tadpoles and frogs. Larger individuals may also prey on smaller rodents (such as mice swimming in the stream). It spawns by migrating upstream from October to January, with the female selecting a suitable spawning site. She uses her tail to create a depression in the rocky and gravelly bottom, where she lays her eggs, which are then covered with small gravel after fertilization.