The swim bladder or air bladder is present only in:

Which of the following features is associated with the aquatic life of fish?

The common name of $Wallago \ attu$ is:

Why is the tuna fish found in the ocean rarely seen in tropical areas?

The presence or absence of which of the following is used to distinguish between bony fishes $(Osteichthyes)$ and cartilaginous fishes $(Chondrichthyes)$?

Which of the following organisms lives in freshwater?