Grunion bluish-green backs and silvery sides and bellies. Their snouts are bluntly rounded and slippery. Silversides differ from true smelts of the family Osmeridae in that they lack the trout-like adipose fin. Young grunion grow rapidly and are about five inches long by the time they reach one year old and are ready to spawn. Adult fish normally range in size from with a maximum recorded size of (La Jolla, Ca., 05-11-05). Average body lengths for males and females are , respectively, at the end of one year; at the end of two years; and at the end of three years.
USS Grunion the Pacific on 24 May. A week later, as she transited the Caribbean Sea for Panama, she rescued 16 survivors of the USAT "Jack", which had been torpedoed by the , and conducted a fruitless search for 13 other survivors presumed to be in the vicinity. Arriving at Coco Solo on 3 June, the "Grunion" landed the survivors and continued on to Pearl Harbor, arriving on 20 June. Departing Hawaii on 30 June after ten days of intensive training, the "Grunion" touched Midway Island before heading toward the Aleutian Islands for her first war patrol. Her first report, made as