Data sheet rainbow trout
Latin name:
Oncorhynchus mykiss, Parasalmo mykiss, Salmo gairdneri, Salmo irideus
Trade name:
Rainbow trout, salmon trout
order name:
Salmonoides (Salmoniformes)
Family:
Salmon fish (Salmonidae)
Genus:
Pacific Salmon (Oncorhynchus)
Origin:
North America
Size (in cm:
until 80
pond size
Content in litres:
1000
water values
Temperature:
up to 25 °C
behavior/stocking
Area:
lower and middle range
Lining:
Carnivores, live food (small fish, insects, worms, tadpoles, water fleas, frogs, maggots, spawn), fishmeal
Behave:
Shoal fish when young, loners, predatory fish, spawn robbers when adults
Number:
single fish
Life expectancy:
up to 7 years
socialization:
no
Difficulty level:
Advanced Engbretson, Eric / US Fish and Wildlife Service, Oncorhynchus mykiss, marked as public domain, details on Wikimedia Commons
General introduction
The fish are originally from North America. They were introduced to Europe in the 19th century as an excellent food fish. In commercial fish farming, they quickly replaced domestic brown trout. Americans are less sensitive and grow faster.
Because of the red meat, the animals are often offered as salmon trout. The color of the meat can be intensified by adding coloring to the feed.
They live in nature in cool, fast-flowing waters. They often stay in the middle of the river in free flow, preferably close to the bottom. Popular places are deep gullies, under waterfalls in the foaming water or at river bends in the countercurrent. The trout are not true to location.
There is worldwide many different subspecies. Some of them live in fresh water, others in salt water. The anadromous forms migrate from salt water to large rivers to spawn. They are referred to as steelheads (the head and back are colored steel blue.). The freshwater forms are known as rainbow trout.
Look
The name rainbow trout comes from that wide, reddish sideband that shimmers in all the colors of the rainbow.
Their body is elongated and somewhat flattened on the sides. The large cleft of the mouth extends to the posterior edge of the eye. The mouth is riddled with many small, pointed teeth.
Fish have one between their caudal and dorsal fins adipose fin. Their caudal peduncle is high and flattened. The back is olive green to blue-green, the belly is whitish.
Except for his stomach entire body with small black irregular dots covered. The points are also found on the slightly forked caudal fin and the adipose and dorsal fins.
Young animals show vertical, dark bars on the flanks. Depending on the subspecies and the environment, the base color can vary. In contrast to the similar brown trout, the head of the rainbow trout is smaller and more pointed. Their lower jaw is further back than the native species.
Behave
As juveniles they live in shoals. From a body weight of about 3 kg, they separate. Then everyone chooses his own fish own territory and inhabits it as a loner.
When young, they capture small amounts of food. tadpoles, worms, insects. The bigger they get, the bigger their prey gets.
They catch insects and their larvae above and below the water. They either lurk behind rocks or other cover, or they chase their prey in open water.
Pond
In the pond, one is mandatory flow to rule. Since the animals need clean, oxygen-rich water, it should have a constant inflow feature. A stream or spring are ideal.
If no natural running water is available, fresh water can be fed into the pond via a pipe. The pipe should be installed 50 cm above the water level so that the water can fall into the pond. It is enriched with oxygen. The water flow should be adjusted so that the volume is changed 4 to 5 times a day.
Pond aerators or water features provide additional oxygen. With a strong filter the pond system is complete. The bottom should be off fine gravel consist. A few larger stones and roots as hiding places promote well-being
gender differences
The reddish side stripes are particularly intense in young males during the spawning season.
breed
Farming trout in a garden pond is difficult. The animals become sexually mature at the age of 2 to 3 years. They spawn at water temperatures around 6 °C, in Europe this is from November to April.
In nature they migrate up the rivers to the source streams. They prefer to spawn on gravelly bottoms near rapids.
The females flap one with their caudal fin spawning pit into the gravel. That’s where they drop the eggs. After being fertilized by a male, the female covers the cavity with gravel.
How long it takes for the young to hatch depends on the water temperature. At 10 °C they need 30 days, at 5 °C 60 days.
In the pond, under optimal conditions (very strong current, very high oxygen content), the fish also get into the mood to spawn. Is to a lot of caregiver experience necessary.
rearing
As long as the young feed on the yolk sac, they stay close to the spawning pit and hide in the gravel there. Then they begin zooplankton to eat.
are rainbow trout spawn robber and sometimes tend to cannibalism. The offspring must move to an extra pond or pool. Even then, individual individuals that have grown faster may eat their smaller siblings.
socialization
A socialization is only with very large fish (interference) possible. All others end up in the thieves’ stomachs.