Salmoniods have a distinct shape and composition to their eyes. Somewhat nearsighted and without lids trout and salmon eyes are sensitive to light. They have a maximum range of approximately twenty feet and can see minute details up close . They see in a cone shape that widens as distance is extended. This is what is called the window. Given the eyes unique location on the side of their body, there are blind spots that are directly behind, above, below and in front. Full body movement is required to see in these locations.
A pallet of twenty four colors can be seen in full light. The last and first color to be visible is blue. In a total absence of light white and black can bee seen as white and black. Certain color combination's are better seen because of the distinct contrast that is created making one of the color enhanced. Perhaps this is the reason a Mickey Finn or Blood Egg can be so effective at times. Sparkling adornments, florescent glows and vivid saturated colors can be seen better in low light and in discolored water.
These fish have no external ears. Hearing is achieved by the use of internal ears as well as the lateral line detecting sound vibrations. There is a tonal range that fish can hear. The human voice is outside that range and can not be heard. Wading staffs, metal cleats and rapid movement can be heard and felt from a great distance.
The sensory ability of smell may be the most highly sophisticated attribute of the genome Oncorhynchus. Able to detect the right or wrong smell in one part per billion puts trout and salmon in the top of this category.
The ability to discern by taste equates to the selective nature of feeding. The simple sensory choice is a matter of what tastes best to the fish at the time of feeding.
This sense is divided into two different categories. Natural feel and testing feel. What is felt can be different than what is felt. Trout and salmon feel every tiny vibration and change in current for a substantial distance. They can even feel these changes happening down stream of their location. Water is denser than air and the molecules will radiate vibration at a faster speed than the water is moving. This is enhanced as the water temperature increases.
In Testing Feel we are using what little ability a fish has to be curious. That momentary lapse in sensory auto pilot that will cause a fish to test if something is food or not. This test is done by the mouth using the other senses of sight, smell and taste.