This problem involves identifying similar relationships between pairs of words. We have the pair "BIRD : AEROPLANE." Here, a bird moves through the air naturally, while an aeroplane is a man-made vehicle that moves through air. The relationship in this pair is that an aeroplane is a mode of transport similar to a bird but used by humans.

We need to find a similar relationship for "FISH : ?". A fish naturally moves through water. Therefore, we are looking for a man-made vehicle that moves through water, akin to how an aeroplane compares to a bird. Among the given options:

• FISHERMAN: A person who catches fish.

• SOFA: A piece of furniture.

• BOAT: A man-made vehicle that travels through water.

• GLASSES: A tool for correcting vision.

The logical choice is "BOAT" as it is a vehicle designed to move through water, just as an aeroplane moves through the air like a bird.

Thus, the correct answer is: