The rivers and lakes of Bayan-Olgii are stocked full of trout, salmon, and other freshwater fish. Fly fishing and ice fishing are especially popular. All of Bayan-Olgii drains into the Great Lakes depression of Mongolia, and is a self contained watershed. There are 5 species of fish that inhabit this watershed including the Taimen, Lenok Trout, Osman, Grayling, and Pike. Fish in Mongolia can be quite big with the Taimen weighing over 30 kg (66 lbs), making the large salmon prized by anglers around the world. Lenok Trout are abundant during late spring and early summer, while graylings are found all over Northern Asia. Osmans are a large carp that is only found in the Lake Uvs drainage area of Russia and Mongolia (covering all of Bayan-Olgii). Fly fishing is great all summer with the best time being July to September, though ice fishing offers the largest catches. The locals prefer fishing during the cold winter months when the thick ice traps fish in a limited number of deep water holes. It is not uncommon to catch hundreds of trout and graylings in a 8-9 days fishing trip.