The Khovd river is spread in region of Altai. We catch mongolian grayilng of size between 40-80 cm and weight around 1-3 kilo there. The Mongolian grayling is the biggest grayling on the world. The next fish are endemic Altai osman which grow up lenght around 100 cm with weight is 4-6 kilo and Artict grayling with lenght around 50 cm. We catch as well the fish in Churgan and Choton lakes. The best term (date) for catch the fish is late of may or start of july. Long of trek is 7 days. I recommend you combine the trek with Altai catching and short trek in Gobi which is the best adventure trek in Mongolia which I provide you like a guide.