What Do Trout Eat? (A Complete Guide to Trout Diet)

What do trouts eat

For many fly anglers and fishermen, understanding what trout eat is not just a matter of curiosity but a key to mastering the art of the catch.

Their diet reflects their adaptability to various habitats, the changing seasons, and prey availability. As opportunistic feeders, their food spans from aquatic insects to small fish species and even includes other trout. 

For those passionate about fly fishing, understanding the ins and outs of a trout’s diet can be beneficial. This article dives into everything there is to know about what trout eat.

What Do Trout Eat?

Trout about to swallow food

At the core of their diet, trout predominantly eat aquatic insects, terrestrial insects, crustaceans, and smaller fish. They also sometimes eat worms, snails, and, on rare occasions, small rodents like mice.

Trout are known for their opportunistic and sometimes selective feeding habits. Their food choices often mirror what’s abundant and accessible in their environment. 

Aquatic insects, such as mayflies, caddisflies, and stoneflies, are among their primary food sources. Terrestrial insects, like grasshoppers and ants that fall into the water, also form a significant portion of their diet. 

Additionally, trout often prey on smaller fish, showcasing their predatory nature. Furthermore, crustaceans, especially crayfish, are a delicacy for trout when they are available in their habitat. 

Their diverse and interesting diet is a testament to their adaptability and survival instincts in varied environments.

Common Trout Species and Their Diet

If you’re serious about fishing for trout, it’s essential to recognize the different species and understand their specific dietary preferences. Here are some common types of trout and their food preferences. 

1. Rainbow Trout (Oncorhynchus mykiss

Rainbow trout

Rainbow trout eat a variety of insects, crustaceans, and small fish. Their diet also showcases cannibalistic tendencies, as they are known to prey on the eggs of fellow rainbow trout. 

In certain habitats, rainbow trout might also feed on terrestrial insects and other small organisms that fall into the water. Check out this list of the best baits for rainbow trout.

2. Brook Trout (Salvelinus fontinalis)

Brook trout

Commonly found in cold, clear waters, brook trout primarily feed on insects, both aquatic and terrestrial. They also have a taste for small fish, crustaceans, and even their own eggs. 

In certain habitats, they might feed on zooplankton and algae, showcasing their adaptability. Brook trout are also known to consume terrestrial insects that fall onto the surface of the water, such as ants and beetles.

3. Brown Trout (Salmo trutta)

Brown trout

Brown trout eat many kinds of food, from insects and crustaceans to small fish species. According to some anglers, they are particularly fond of terrestrial insects like ants and beetles. 

In some regions, they might even consume small mammals, highlighting their opportunistic nature. Brown trout in streams might also feed on larvae and nymphs, especially during their early stages.

I recently came across a study about brown trout and their feeding habits. The research focused on the factors that influence the dietary shifts of stream-dwelling brown trout as they grow in size. 

One of the most intriguing findings was the timing of their switch from aquatic to surface prey. This transition typically occurs when the trout reaches a body length of 81 mm or 3.2 inches. 

The study also emphasized the importance of fish length, availability of benthic invertebrates, brown trout density, and water current velocity in influencing their source of food. 

4. Lake Trout (Salvelinus namaycush)

Lake trout

Predominantly found in deep, cold lakes, lake trout are top predators, primarily feeding on other fish species. They also consume insects and crustaceans when they are available, showcasing their varied diet. 

In some instances, usually in deeper lakes, these trout might also feed on aquatic insects like midges and mayflies.

5. Cutthroat Trout (Oncorhynchus clarkii)

Cutthroat trout

Native to the freshwater streams and rivers of North America, cutthroat trout are a favorite among anglers. They primarily feed on aquatic insects, crustaceans like scud, and smaller fish. 

During early summer, when certain insects are in their larval stage, cutthroat trout are known to feed heavily on them. They also eat worms and terrestrial insects that fall into the water column. 

In some regions, especially where common trout food is not abundant, cutthroat trout might display cannibalistic tendencies. They are known to eat smaller trout, including their own species. 

Additionally, in waters where salmon are present, cutthroat trout will also feed on salmon eggs, capitalizing on this rich food source.

Meanwhile, here is a great guide we have put together on how to differentiate cutthroat from rainbow and cutbow trout.

Factors Influencing Trout Diet

Evidently, the dietary preferences of trouts are quite diverse, but what are the factors that determine their food choices? Surely, knowing these key factors will increase your luck when fishing for trout.

Here are some of the main factors affecting the trout diet:

  • Availability of Prey: The presence or absence of certain prey in their habitat can dictate their food choices. For instance, in a habitat rich in aquatic insects, trout might feed predominantly on them.
  • Seasonal Changes: Different seasons usher in varied prey, thereby influencing trout diet. For instance, during spring, the emergence of certain aquatic insects might become the primary food source for trout. This seasonal variation in diet has been observed by certain studies in various trout habitats, emphasizing the role of seasonal changes in trout diet.
  • Breeding and Spawning Seasons: These periods can incite a shift in the dietary preferences of trout. For instance, during spawning seasons, some trout species might consume fish eggs.
  • Water Temperature: The temperature can affect the metabolic rate of trout and the availability of certain prey. In colder temperatures, trout might feed less frequently but opt for more substantial prey like small fish over other common food. On a related note, a study by Dunnigan & Terrazas on regulated rivers found that variations in water temperature significantly impacted the annual growth rates of trout, underscoring its role in trout physiology and behavior,
  • Presence of Predators: The presence of big fish predators can influence where trout feed and what they eat. For instance, in waters with larger predatory fish, trout might stay closer to the surface of the water or hide in vegetation. Usually, this is also the time when they eat insects.

In essence, while trout are opportunistic, their diet is significantly molded by their surroundings and the food sources available to them. 

Top 10 Baits for Trout Fishing

Worms as the best trout bait

For those passionate about fly fishing, selecting the right bait can make all the difference. Here are some of the most effective ones for trout:

  • Worms: A classic choice, often irresistible to trout, are worms. Worms mimic the natural prey found in their habitat, making them an effective bait for trout in streams and lakes.
  • Aquatic insects: Mayflies, caddisflies, and stoneflies are top picks. These insects are a significant part of a trout’s natural diet, especially during their hatch season.
  • Crustaceans: Crayfish, when available in the habitat, make for an excellent trout bait. These fish are a high-protein source, making them a favorite among larger trout.
  • Small fish: Minnows and other small fish species are a favorite for wild trout. These mimic the smaller fish that trout naturally prey on, especially in deeper waters.
  • Terrestrial insects: Grasshoppers and ants can be very effective as trout bait. These insects mimic the terrestrial creatures that accidentally fall into the water, becoming easy prey for different species of trout.
  • Nymphs and larvae: These are especially significant in a trout’s diet. Nymphs and larvae mimic the early stages of aquatic insects, which trout love to eat. This also makes fly fishing nymphs effective for catching trout.
  • Fish eggs: Fish eggs mimic the natural prey during the spawning season when trout exhibit cannibalistic tendencies.
  • Leeches: This high-protein choice is hard to resist for trout. Leeches are found in many trout waters and can be an effective bait, especially for larger trout.
  • Mice: For larger trout looking for a substantial meal. Mice mimic the larger prey that big trout might occasionally feed on.
  • Artificial Flies: Mimicking natural prey can be very effective. Flies designed to resemble aquatic insects or terrestrial creatures, such as the perdigon fly, can be particularly effective when you’re fishing in habitats rich in these prey.

All in all, there is a wide range of options when it comes to trout bait. A valuable tip when fishing for trout is to learn about what trout are feeding on in your chosen area. This knowledge can significantly enhance your chances of a successful catch.

On a related note, watch this video to learn how to set trout bait:

How To Set up & Fish For Trout, EVERYTHING You Need To Know!

Frequently Asked Questions

A school of trout

What Is the Best Food for Trout?

The best food for trout largely depends on their habitat and the season. However, aquatic insects, especially mayflies, caddisflies, and stoneflies, are consistently a top choice.

What Do Trout Eat in Lakes?

In lakes, trout primarily feed on smaller fish, crustaceans, and any available aquatic insects. They might also consume terrestrial insects that accidentally fall into the water.

What Do Trout Eat in the Winter?

During winter, trout have a slower metabolism. Hence, they primarily feed on minnows and other small fish due to the reduced availability of insects out in the wild.

Final Thoughts

Trout, with their diverse diet, are a testament to nature’s adaptability and survival instincts. Their varied diet, influenced by their habitat, season, and available prey, offers a fascinating insight into their world. 

For fly fishermen and anglers, understanding this diet is not just about increasing the catch rate; it’s about deepening the connection with nature and the sport. 

Whether you’re by a serene lake or a gushing stream, let the world of trout offer you insights, challenges, and, most importantly, a memorable fishing experience.

Hopefully, you’ve learned a lot from this comprehensive guide. If you have any comments and suggestions related to the trout diet, leave them below!

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