To survive the lake trout requires a proper environment with suitable depth, temperature, and oxygen, and enough forage fish to grow to a good size. They prefer lakes with a depth greater than 50 feet, ideally closer to 100 feet deep, and can sometimes be found in depths up to 600 feet in the summer. They need cold water of about 50° F. (10° C). Oxygen is important but oxygen produced through plant life can be detrimental. Lakes with extreme weed growth can damage lake trout reproduction during the winter stagnation period.

As with all other fish, the growth rate is largely dependent on the availability of forage fish. It is not uncommon for lake trout to attain weights in excess of 40 pounds. However, the average fish is less than ten pounds. One of the most probable reasons for this is that the fish's environment does not contain an adequate food supply.

Although lake trout vary their diets, eating everything from plankton to freshwater sponges, there are one or two staples in a particular lake that contribute to the growth of good-sized fish. Crustaceans, insects, whitefish, smelt, sculpins, shiners, sticklebacks, suckers, perch, the ling, trout perch, alewife, and ciscoes make up the lake trout's menu. Of these species, however, the whitefish is the one most closely associated with the lake trout. Those lakes that contain only smaller food fish such as the emerald shiner generally produce smaller fish.

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