Fly Fishing for Cohos (Silvers) is at its best in August and September. Silvers are very likely the most fun of all the Alaska salmon. Silvers are fished very close to tidewater where the chromers are most prevalent. As they remain in fresh water, they to morph into a bizarre red and black, hook jaw monster. Most silver Salmon weigh between 8 and 15 pounds and are very aggressive towards flies and spinners.