Tiger trout
The tiger trout ( Salmo trutta fario x Salvelinus fontinalis ) is a cross between brown trout and brook trout .
description
The tiger trout owes its name to its distinctive, often golden yellow markings, which are vaguely reminiscent of a tiger's skin . The eye-catching coloration is emphasized by the reddish belly, which it inherited from the char. The basic color is gray-green with a light grain. Otherwise it has an elongated, torpedo-shaped body, slightly compressed at the sides and, like all salmonids, in addition to dorsal, thoracic, ventral and caudal fin, also an adipose fin. Tiger trout can grow up to 80 centimeters, weigh seven kilograms and reach an age of 10 years.
distribution and habitat
Brook trout have 84 chromosomes and brown trout 80. Therefore, crossbreeding of the two species in the wild rarely leads to viable young. However, in Wisconsin it has been observed that tiger trout also occur naturally in the state's small rivers, even though the US state discontinued its stocking program in the late 1970s. With the improvement in water quality over the past 20 years, the brook trout population has grown by leaps and bounds, as a result of which misguided dairymen of this species were more likely to encounter rogner of brown trout, possibly leading to more frequent hybrids.
The tiger trout can live in cold and oxygen-rich waters, both flowing and standing (such as mountain lakes). She was released in waters in Europe and North America. In Bavaria , according to Section 22 (4) AVBayFiG, it may only be kept in closed waters (ponds) from which it cannot escape. According to Section 11 (8) AVBayFiG, it may not be released if it is caught in open waters.
Way of life
The tiger trout hardly needs any shelters and is therefore, due to its extremely wide food spectrum, also suitable for colonizing straightened and rapidly flowing streams and, above all, for stocking the source regions of mountain streams. The release of non-native fish is, however, prohibited in parts of Germany, at least in Bavaria (Ordinance on the Implementation of the Fisheries Act for Bavaria, AVFiG § 19 Paragraph 5 Sentence 1). These fish may only be kept in drainable and closed off fish ponds, so-called closed waters, for the purpose of fish breeding and production.
Reproduction
Tiger trout are sterile . The hybrids cannot reproduce further , but only emerge from new crossings of the original species. Nevertheless, a sexual dimorphism in female and male fish can be determined through external sexual characteristics . However, the female tiger trout do not develop gonads . The males, on the other hand, develop testicles as well as secondary sexual characteristics such as the spawn hook , hump, dark and thick skin. During the spawning season, the muscle meat of the males is lighter in color.
Tiger trout are mostly raised in fish farms, where brown trout eggs are fertilized by brook trout milk (satisfactory hatching and survival rates can only be expected if the brown trout is used on the female side), after which the fertilized eggs are subjected to a heat shock, which ensures a higher survival rate.