In broad terms, variation among lake trout is determined by the available food supplies and the genes of the trout themselves. Unlike river trout, which obtain the bulk of their food from the flow at or close to the water surface, lake trout must swim in search of their food. Only a small proportion is gathered at the surface. The vast majority of lake trout seek out the more productive shallow water at the lake margins or amongst skerries and islands in the lake. Here they are likely to find the most plant growth and the water animals that feed off the plants.
Some lakes produce large numbers of crustaceans, such as freshwater shrimps, hog-lice and crayfish.
In larger lakes it is possible to find trout in several-different niches, often with different coloration. Some of the trout might patrol areas of weedbed or shallow rocky shores, where aquatic snails and crustaceans are abundant. These will tend to have the plainest coloration of all. So, although it may be possible to identify a lake trout purely on the-basis of colour, an individual gillaroo, Kamloops rainbow or Yellowstone cutthroat may well be different ingeneral coloration from others in the same lake. Yet despite this variation it is usually possible to recognize a particular variety because the underlying features are always present.