All fiish species have a set of senses that enable them to survive in their aquatic settings. When the pond water is clear fish rely on their vision to find food and avoid predators. When the pond is muddy from heavy rainstorms, they rely on their hearing and lateral-line system. Even though every fish has each of the senses, it varies from species to species.
Vision:
In all fish, the retina of the eyes is equipped with rods and cones. Fish who are found in shallow water have better color vision then those that are deep-water species. Good color vision would be meaningless to fish in deep water because in the depths water acts as a color filter. Red disappears at 10 feet and yellow at about 20 feet. While blue may be visable at 50 feet or more if there is adequate light penetration. And fish that have color vision might not have night vision, because they lack enough rods in their retinas. Just how far a fish can see depends more on the clarity of the water, then their visual acuity.
Lateral Line System:
This type of sense enables fish to pick up vibrations from the water to help them detect predators. The lateral line is a row of pores along the sides of each fish, extending from the gill to the base of the tail. These pores are connected to a series of nerve endings that can sense even the slightest vibrations and transmit them to receptors in their inner ear. Using this lateral line, the fish can figure out if predators or prey are present and how big they are and how fast they are moving and in what direction they are going. This lateral line also helps fish who like to swim in unison to stay together.
Hearing:
Fish have inner ears which are made up of tiny bones that pick up sound and semi-circular canals that help maintain their equilibrium. They do not have an ear drum, but instead vibrations are sent to their ears through their body tissues.
Smell and Taste:
Most fish have acute sense of smell and can detect odors of nearby predators and prey, if the current alouds it. But some fish rely on scent more than smell. In some fish this sense of taste helps them find food in muddy water or on the bottom of the pond. Some fish like catfish have taste buds in their whiskers and on their skin to aid in the finding of food.
