Rainbow Trout

All of Patagonia salmonids are exotic species, including Rainbow Trout (Oncorhynchus mykiss) that were introduced here, from North America in the early 1900s for sport fishing.
It has a small head and a long body, with a bright blue or green color on its flanks, and a silver white color on its abdomen. In the middle of each side it has a longitudinal striking red stripe, inspiring their name. This color is typical of the species, but it may vary from one trout to another, and even disappear in some of them.

The anadromous form called "steelhead" migrate to the ocean, though they must return to fresh water to reproduce, do not necessarily die after spawning (they may spawn as many as four times). River resident rainbow trout are generally darker and more brilliant. They always have dark spots on their heads, backs, bellies and across their dorsal fins and caudal fins. Rainbows occur in well-oxygenated lakes and streams where the temperature normally doesn't rise above 12°C in summer. There is also an important variability as regards color in relation to the spawning season, having mature specimen a darker and brighter pigmentation.

It is possible to find it in almost every river and lake in the province of Neuquén, and it is highly appreciated by anglers for its combativeness and size. Rainbows range from 12 to 36 inches in length, reaching as much 10 kg. in lake environments. It feeds on insects, mollusks, crustaceans and fish.

Brown Trout

Brown Trout (Salmo trutta) is probably the most popular Salmonidae among anglers, since it lives in hardly accessible environments, in places difficult to reach with a fly, adding to this its characteristics, such as evasive, unpredictable, aggressive, and enormously cunning, which makes it really difficult to catch.

They are generally olive-green to steely blue in color with a silvery white belly. The sides are lighter in color and there are numerous spots over the upper body, head and tail. In rivers, its loin is darker brown, with a golden brown color on the flanks and a white yellowish tone in the abdomen, with spots scattered on the body: green and brown on the upper part, and on both sides they mingle with red dots wrapped in pale circles.

The brown trout were stocked from Europe and Chile. Prefer cold, this species has a somewhat higher temperature preference of about 60-65 F°, or 15.5 - 18.3 C°), well-oxygenated upland waters, especially large streams in mountainous areas. Cover is important to trout, and they are more likely to be found where there are submerged rocks, undercut banks, and overhanging vegetation.

The brown trout is a medium sized fish, growing to 20 kg or more in some localities although in many smaller rivers a mature weight of 1 kg (2 lb) or less is common. May live for several years although, there is a high proportion of death of males after spawning and probably fewer than 20% of female recover from spawning. The migratory forms grow to significantly larger sizes and may live longer. Brown trout are active both by day and by night and are opportunistic feeders. While in fresh water, the diet will frequently include invertebrates from the streambed, small fish, frogs, and insects flying near the water's surface. The high dietary reliance upon insect larvae, pupae, nymphs and adults is what allows trout to be a favoured target for fly fishing.

The spawning behaviour of brown trout is similar to that of the closely related Atlantic salmon. A typical female produces about 2,000 eggs per kilogram (900 eggs per pound) of body weight at spawning. Brown trout rarely form hybrids, almost invariably infertile, with other species. One such example is the tiger trout, a hybrid with the brook trout.