RAINBOW TROUT

Local name:
ružičasta pastrmka (pink trout)
Latin name:
Oncorhynchus mykiss
Length:
from 35 to 70cm
Maximum weight:
up to 15,8 kg
Time of spawning:
beginning in early spring, end in May

 

Description and structure:

The rainbow trout is somewhat wider and stronger than the brown trout. The body, including the fins, is covered with dark spots (visible on the back, the anal and the tail fins) and spindle-formed, like with all members of the Salmonidae family. Compared to the brown trout, it has a slenderer body covered with numerous small scales, and also a smaller head ending with a somewhat smaller mouth. The back is dark green, and on the sides (which sometimes sparkle silvery) there is a rainbow-coloured line which sometimes looks red, from the gill cover up to the caudal peduncle (because of which, it is called “rainbow trout” in some languages). The belly is white, sometimes yellowish or pinkish (hence the name “pink trout”).

Habits, habitat, distribution:

It originates from North America. It was brought to our region in 1893, when some bodies of water were stocked with it. It adjusted very quickly to both the rivers and the lakes, and now lives in the same way as our brown trout. It is raised on a large scale in fish farms mainly for its tolerance of temperatures up to 25º. In nature, it only reproduces in precisely defined places. It does not stay long in open water. It is less demanding than the brown trout in terms of water quantity and temperature.

In some bodies of water, it reaches a maximum weight of 10 kg. It is a great predator and attacks all baits. Three times smaller specimen are considered a trophy. The average fishing weight is from 200 to 900 grams. As small fish, it is fed with plankton and small aquatic animals, and subsequently transfers to more coarse food. When it gets older, it becomes a predator that does not allow other fish to reach food. The trout and its relatives hide a glutton of very quick and gracious movements. It stays mostly in the middle of the water surface, where it constantly circles – one moment on the bottom, then on the surface, and then again between the two water layers. In rivers, it looks for deeper zones and searches through all hidden corners of its new habitat. As time passes, it has a tendency to go downstream. Since its birth in a fish farm, the rainbow trout lives together with other trout, more or less squeezed next to each other. When released to freedom, they keep this habit. They rarely live alone. Their group instinct, acquired during their growing up, is too strong. When they are in a natural environment, they eat almost everything they find: larvae and various insects, worms, crustaceans, fingerlings and small fish. Fishermen offer them baits like granules, feed they have been most acquainted with since they were fed with it from an early age.

Fertilisation:

In their native environment, trout reproduce in the third year of its life for female trout, and the second year of life for male trout. They spawn in the early spring (March-April), up until May, in the upper flows of rivers according to the water temperature (10oC up to 15oC). Then they get more expressive colours on their bodies, the so called spawning rush. At that time the meat colour also changes and they get a stronger fish odour. They lay 500 to 5,000 eggs. When the male fertilises them, incubation lasts two to three months, sometimes longer, depending on the water temperature. The juvenile fish grow quickly, feeding on insects and their larvae. Trout are sexually mature between the second and the third year, when they are 20-25 cm long.