How do fish smell and see?

Some fishes are primarily “eye-minded,” depending for the most part on their eyes for sensory contact with the world about them. The striped bass is one of these, and the pike is another. Other species, such as the brown bullhead and the sturgeons, are more “taste-minded” or “smell-minded.”

This type often has barbels, or “feelers,” with which to explore its surroundings. Viewing objects through the water presents difficulties not encountered in air; nevertheless, numerous fishes show real ability to see sharply. Witness the accuracy with which the trout or the bass strikes at the fisherman’s fly. So far as known, fishes are also able to perceive colors. Fishes have ears, although they are hidden away inside their heads. Like other vertebrates, fishes use their ears to keep their balance and to detect sound waves.

Fishes are also equipped with a system of small canals that lie under the skin and communicate with the exterior by a series of pores. Part of this complex organ is visible externally; it is known as the “lateral line,” and is quite apparent in the striped bass. It “feels” many of the numerous vibrations transmitted through the water, thereby acting as a sort of long-distance touch. Not all fishes have lateral lines, however.

In fishes, the nose is not connected to the mouth, except in a handful of species. Fishes use their noses only to smell, not to breathe – with the exception of the electric stargazer and its very close relatives, and perhaps certain eels. Smell and taste are rather difficult to tell apart under water; at any rate there is a lot of evidence that fishes can be acutely sensitive to chemical substances.

Many of them have taste buds over much of their bodies, and thus are able to detect the presence of food even with their tails. Usually barbels and other sensory organs are especially well equipped with taste buds.