Dogtooth tuna are not like other tunas; they are slow-moving demersal fish (bottom dwelling) and tend to stay in one area.
Dogtooth tuna (Gymnosarda unicolour) can grow up to 2.5 m and weigh 130 kg, and unlike other tunas, they have white flesh. Smaller dogtooth tuna are more commonly found near shallow reef areas and larger ones near deep reef drop-off areas. Their diet consists of schooling fish including rainbow runners. Dogtooth tuna are locally very rare at Christmas Island. They are more common on Cocos (Keeling) Islands but more data on their current status is required.