Question

A scaleless fish is
a. Scoliodon
b. Remora
c. Catfish
d. Labeo

Answer 1

Hint: Every fish is mostly covered with the scales, but some fishes covered with exoskeleton, mucus, boney plates, etc. Scaleless fishes do not have scales and instead of scales, they have thick mucus layers for protection.

Complete answer:
> Option A - Scolioden is a genus of sharks. The sharks are covered with exoskeleton which is an evolved form of scales. This exoskeleton is formed by placoid scales. So it is not a scaleless fish. So this option is wrong.

> Option B - Remora fish has a long and flattened head and short body.it is covered in small smooth scales. Thus it is not a scaleless fish. So, this option is wrong.

> Option C - The catfish body is covered with the mucus .it does not contains scales because it respirates through the skin i.e cutaneous respiration, but in some catfish, the body is covered with the bony plates called scutes.but mostly catfishes are naked without scales. So it is a scaleless fish. So this option is correct.

> Option D - Labeo is known as the carp fish. It is found in clear and slow streams and rivers. So it is the wrong option.

Hence, the correct answer is option (B).

Note: There are many types of fish scales. Also, they come in all sorts of shapes and sizes. There are two types, one is scaleless fish and others have scales. Scaleless fishes have very much thick skin. This skin produces proteins and mucins, which form slime and excreted through glands.