A fisherman caught an organism in the sea. It looked strange to him because it was without scales. The organism might be
Petromyzon is a cyclostome which is without jaws, has a circular mouth and is devoid of scales.
Ichthyosaurus is an extinct sail back reptile without scales.
Latimeria (a coelacanth) is a lobefin fish with cosmoid scales.
Torpedo is an electric ray with placoid scales.