Lake Trout vs Rainbow Trout (One Is Not Like The Other!)

Lake Trout Vs Rainbow Trout

lake trout vs rainbow trout differences

Introduction

With the menagerie of trout species available to catch for the willing angler, it can sometimes be confusing to distinguish between any of the one species you may have a chance at catching. When fishing lakes or rivers, you may encounter different species of trout on the end of your line. 

In this guide, we are going to look at the visual and biological differences between Lake Trout and Rainbow Trout. Two species of fish that cohabit some bodies of water and could both end up on your same stringer of fish. Stay tuned for more guides on how to differentiate between other species of trout. 

Biology

Lake Trout

Lake Trout are in fact not a true trout species. They are actually a species in the group referred to as “char”. More similar to Brook Trout and Dolly Varden than their more distant Rainbow and Brown Trout cousins. The native range of Lake Trout has a relatively limited distribution, confined to the northern part of North America. Primarily native to the deep natural lakes of Canada, Alaska, and some of the northern contiguous United States. They have since been introduced has a sportfish in lakes across the U.S. and the world. They are a fish that prefers deep lakes and can be fished for at depths pushing 200 feet in certain conditions. Some populations are highly predatory while others eat lots of small food such as plankton species. 

Rainbow Trout

Rainbow Trout are the second most popular sportfish in the U.S. behind Largemouth Bass. They are stocked for recreational angling in water bodies all over. Historically, they were native primarily to river systems in the Pacific Northwest and West Coast in and around the Columbia River Drainage. They are a species of fish well suited to swimming in fast current, jumping, and covering miles through water. They are a popular sportfish that can be fished for in stocked and wild populations in lakes, streams, and reservoirs across the U.S. On average much smaller than Lake Trout, though they are enjoyed as a sportfish by anglers all over. Known for their good table fare and willingness to take lure or bait, it is easy to see why they are such a popular sportfish.

Identification

Now let’s look at some of the key characteristics at telling the difference between a Lake Trout and Rainbow Trout when you have one in your hands. 

Spot-Patterns

Lake Trout spots are one of the most definitive ways to distinguish between that and a Rainbow Trout if you are fishing a body of water with both species. Lake Trout are characterized by “light spots on a dark background”. The spotting will be randomly distributed across the whole body from top to belly and will be lighter and more grey than the body color.

Rainbow Trout on the other hand, are characterized by “dark spots on a light background”. Rainbow Trout will have dark spots with irregular edges distributed evenly from the front to the back of the body. Generally, these spots are more concentrated on the upper half of the fish and less so on the lower sides of the fish. 

Color is not the most reliable indicator to use for fish as some overlap can occur. Use it in conjunction with other ID traits. 

Lake Trout generally range from a washed out silver to a dark olive green and many shades in between. Some individuals may be so dark green that their top half may appear nearly black. The belly is generally a creamy white with heavy spotting occurring down to this color transition. 

Rainbow Trout can have a good bit of variation in coloring. The best indicator of a Rainbow Trout is the presence of a nice pink stripe down the lateral line. However, not every Rainbow Trout will always have a pink stripe. Generally, Rainbow Trout exhibit a much darker green or bluish colored back and lighter colored flanks extending to a white belly. The green on the upper half will appear to be lighter and more blue in color than the green found on Lake Trout. 

Tail Fin

Lake Trout are very much characterized be a deeply forked caudal fin (or tail fin). This trait will be a very reliable indicator that you are looking at a Lake Trout and not another species of trout. Think of their tail as looking like a “V”.

Rainbow Trout also have a slightly forked fin. However, it is nowhere as deep of a fork as a Lake Trout. A rainbow trout has more of a “depression” or indent in the middle of their caudal fin. Lake trout have a nice deep “V” in their tail. 

Size

Lake Trout are the behemoths of the trout world. They evolved to live in big deep lakes and their bodies followed suit. The largest recorded top out over 100 pounds and 4 feet in length! On average, the Lake Trout you catch in a lake are going to be larger than your average Rainbow, Brown, or Brook Trout. Catches of Lake Trout between 18 and 40 inches are commonplace. 

Rainbow Trout did not evolve in large deep lakes as did Lake Trout. Being a fish more suited to life either living in or migrating up rivers, they are smaller and more sleek to contend with the flowing river currents. While Rainbow Trout can surely reach sizes larger than 30 inches, that is certainly the exception to the rule. On average, Rainbow Trout caught by most anglers will be between 10 inches and 24 inches or so. 

Final Thoughts

There is always going to be lots of individual variation between individual fish. As such, reliably identifying fish species can at times pose some challenges to an untrained eye. When it doubt, take good photos and consult an expert. Likely a local fisheries biologist or wildlife officer in your area. 

difference between lake trout and rainbow trout

About the Author

When I'm not bass fishing or looking for steelhead in my home state of Oregon I can be found working on house projects dreaming of my next fishing adventure. I started this website to share just some of the things I've learned along my fishing journey, and the many things I'm still learning. Enjoy!