Unlike humans, fish don't have 3-D vision. That's because their eyes are on the opposite sides of their heads. But what they lack in binocular vision, they make up for with extremely acute interrelated senses of smell and taste, which they rely on to perceive their environment. Some fish use smell to help them find a safe place to lay their eggs. Migrating salmon can recognize the odor of their home stream. Sharks, rays, eels and salmon have such fine-tuned olfactory rosettes (the organs that detect scents) that they can smell chemical levels as low as one part per billion in the water around them.
Fishes' ability to taste is similarly well-developed. Many species have taste buds not just on their tongues, but on their fins, face and tail area as well. They're actually capable of tasting food before they have it in their mouths. Catfish have the most sophisticated palates of all. They're literally covered from head to tail with taste buds. Even their whiskers have taste buds. That enables catfish to scavenge for food even in muddy, murky water.