How Big Do Brown Trout Get? Catching Monster Browns

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Danny releasing the brown trout in the water.

Brown trout can grow over 40 pounds depending on where you target them. On average, you’ll find them in most bodies of water in the 1-5 pound range. The United States and New Zealand offer anglers the best access to trophy brown trout, but European, African, and Asian countries also have populations.

Brown trout offer anglers some of the world’s most exciting game fishing opportunities. They live in beautiful locations, grow to impressive sizes, and challenge anglers of all skill levels. As long as you can find suitable conditions for them, you have a chance at landing some impressive fish. 

Brown Trout Record

If you’re familiar with trout fishing, you’re familiar with the world-class trout in New Zealand. Whether you’re after rainbows or browns, you’ll consistently catch trout around 10 pounds. The world-record brown trout was caught in 2020 in the Ohau Canal in Twizel, New Zealand. 

The angler caught a 44 lbs 5 oz fish on a spinning rod with a jig and six-pound test. The previous world record was caught in that same canal a few years prior. The Ohau Canal is the perfect trout fishery. 

The water is clean, food is plentiful, and it is downstream of a salmon farm. Pellets wash downstream, helping fatten up the resident brown trout. Since the brown trout in the Ohau Canal have access to an unnatural amount of food, they can grow rapidly. Plus, they have ample room to move around and enough cover and structure to hide in. 

The United States brown trout record sits at 40 pounds and 4 ounces. It was caught in the Little Red River in 1992 on a spinning rod with a 1/32-ounce jig and 4-pound test. It took 18 minutes for the angler to land the fish. 

Anglers who spend time fishing in the Great Lakes region have access to huge brown trout. Browns over 20 pounds are caught in the lakes and tributaries yearly. 

Average Brown Trout

The everyday United States brown trout angler isn’t going to land many brown trout over 10 pounds in their life. On average, brown trout are between 1 and 5 pounds and measure 10 to 20 inches. If you’re targeting wild and native brown trout, most sit in the 1- to 4-pound range. 

Stocked brown trout can grow over 4 pounds if fed with enough pellets and live in water that sustains yearly holdovers. If they don’t survive throughout the warmer months, they don’t have a chance to get over a few pounds. 

Most of the brown trout I’ve landed throughout Minnesota, South Dakota, Colorado, and Montana weigh around 3 pounds. I’ve caught larger browns in some major Western rivers, which provide an amazing fight. 

Anglers who spend time fishing for brown trout in their natural waters in Europe can land some monster fish. European brown trout weigh an average of 4 to 10 pounds and grow to around 20 inches.

Brown trout in a net.
Wild Brown Trout

How Fast Brown Trout Grow

A few different factors determine how quickly a brown trout can grow. If all conditions align, brown trout can live to the average 5-year life expectancy.

Water Temperature

Brown trout are some of the most resilient fish in the trout family. They can survive various changing conditions, but consistency encourages growth. Brown trout need water around 65 degrees. If there’s a warm spell and water temperatures sit above 65 degrees for an extended period, brown trout won’t grow and could die. 

Water temperatures that hover between 50 and 60 degrees are ideal for the most growth. Brown trout won’t exert themselves while hunting, and their metabolisms don’t slow to preserve energy. 

Cool, oxygenated water that doesn’t fluctuate excessively in temperature leads to the largest fish. 

It’s not easy to find water temperatures that don’t fluctuate outside of 50-60 degrees, but if you can, you have the potential to find some trophies. 


Brown trout need constant access to insects, crustaceans, and smaller fish. While insects make up most of their diet, they won’t grow over 5 pounds without crustaceans and smaller fish. These food sources are filled with more fat and protein, keeping the fish healthy and growing.

A high mountain stream with only insects isn’t always going to produce the most fish. An alpine lake with large populations of minnows and crayfish will lend itself to larger brown trout. 


Brown trout won’t grow to trophy size if they’re constantly dodging predators. Not only are they stressed, but they’re often eaten before they have the size and strength to defend themselves. Predators like bass and pike eradicate brown trout populations and prevent them from growing as large as possible. 


Anglers heavily pressure some bodies of water. The more pressure a body of water receives, the more stress fish endure. Pressured fish struggle to grow to trophy size. They try to avoid being caught and spend time dodging unnatural foods. An uninterrupted body of water lends itself to the best opportunities for growth. 


Some gene pools are better than others. Wild brown trout that thrive in large alpine lakes likely have phenomenal gene pools. However, a stocked or crossbred population may struggle to grow to that trophy size due to an unnatural gene pool. 

Anglers who spend time fishing in Europe or New Zealand find brown trout with extremely pure genes. European brown trout are native to those waters, and New Zealand’s browns thrive due to ideal water conditions.

Danny holding a brown trout.
Wild Brown Trout


Brown trout need room to grow. Having plenty of water to travel for food is best. A brown trout that lives fighting the current and working for food struggles to reach trophy size. However, a brown trout that lives in a lake with perfect water temperatures and little work required to survive has a far better chance of reaching trophy size. 


The population of other fish is the final factor that impacts a brown trout’s size. A lake overrun with brown trout and other fish isn’t going to produce giants. The competition for food and habitat is immense and negatively affects their growth.

A lake or river with a healthy population allows trout to have their own area and not have to fight for food. 


Brown trout are one of the larger fish in the trout family. If the conditions align, they have the genes and resilience to reach double digits. Water temperature, food, predators, fishing pressure, genetics, habitat, and other fish populations all impact the growth of brown trout.

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