Shimmerfish can sustain speeds of up to 19 miles per hour, with short bursts of more than 25 miles per hour. Their lungs are adapted to allow them to dive to depths of more than 1,000 feet for short periods of time. In one day, a shimmerfish eats nearly one-third of its weight, mostly in fish and squid. Shimmerfish reach maturity at about six years old, at which time their previously dull skin becomes shimmery. They mate in the spring and have a gestation period of eleven or twelve months.
Calves swim and breathe minutes after birth.
Shimmerfish have a language composed primarily of clicking sounds and whistles. These also act as part of an echolocation system, similar to that of a bat, enabling the shimmerfish to navigate and detect prey. Shimmerfish have a gland in the head that holds a small quantity of valuable oil, which is used to lubricate delicate mechanisms. Each shimmerfish gland holds about one ounce of oil, which sells for between one and five gold pieces. Also, raw, uncured hide sells for about two gold pieces, and a cured shimmerfish hide is a beautiful thing worth at least 10 gold pieces.