Judging from your description, Balaam fish, whose scientific name is blue round sole, is also known as stickleback fish, stick fish, pond fish, yellow fish, pond fish and cooked fish.

A species of the genus Haliotis in the family Haliotidae of Perciformes. The body is spindle-shaped and slightly flattened. The fat eyelid is well developed, reaching the middle of the eye from front to back, and only a long slit is exposed in the center of the pupil.