Keeping Trout as Pets

An active freshwater fish, the trout thrives in cold temperate regions in the wild. Recent trends, however, see more aquarists attempting to keep these fish in a domestic setting. Captivity is certainly not an ideal situation for this large carnivorous fish and, in fact, it is illegal in many states. In regions where keeping trout is not illegal, it requires a hefty financial investment and thorough knowledge of this Salmoninae subfamily in order to simply keep the fish alive.

The Legalities of Keeping Trout as Pets

Before looking at what it takes to keep a trout as a pet, it is important to consider the legalities. In most states within the United States, it is illegal to keep native fish in the home or on private property without the appropriate state and federal permits. These permits are almost exclusively limited to creatures that have been bred and raised in captivity. Permits are also issued to licensed wildlife rehabilitation professionals. These permits, both federal and state, must be obtained before obtaining the native wild species in order to adhere to federal and state regulations. It is also important to note that there may be specific regulations that apply to the size of the fish that may be kept in captivity.

Penalties for keeping native fish as pets without the appropriate licenses vary by location, however, they can include fines of $10,000 and loss of all hunting and fishing privileges within the state for life. Penalties may also include arrest and a felony charge.

Legally Keeping Trout in Captivity

When trout are kept legally in captivity, there are a number of things that must be considered in order to keep the fish alive in humane conditions. These things include a complete understanding of the variety of fish, the diet of the fish, the space requirement of the fish, the environmental needs of the fish, and precautions for the health of the fish.

Types of Trout that Are Frequently Kept in Captivity

There are two types of trout that are most frequently kept in captivity – the freshwater brown trout (Salmo trutta morpha fario) and the rainbow trout. To keep these fish healthy while in captivity, it is important to have a complete understanding of each species.

The Brown Trout or Salmo trutta morpha fario

The Brown Trout

Native Habitat

The freshwater brown trout is native to Europe and its native range extends from northern Norway and Russia to North Africa and from Iceland to Afghanistan and Pakistan. This species of trout has been introduced to other habitats globally, however, and has quite successfully established itself in these areas which include North and South America.


The brown trout averages in length between 7.9 to 31.5 in inches, but they can reach as large as 3.3 feet! The average weight of this species of brown trout is around 4 1/2 pounds but have sometimes been known to reach up to 29lbs!


The brown trout is, as its name suggests, brown in coloration, however, this can vary from a brassy tawny color to an olive brown. The back of the fish features brown or black spots. The sides of the fish are lighter, with a tan coloration, and have orange or red spots. Males of the species tend to have brighter coloration than the females.


In their natural habitat, the brown trout tends to live to an average age of 5 years, reaching maturity between 1 and 3 years. It is not uncommon, for a brown trout in an established natural population to live to over 10 years; some may even live to 20 years!


The brown trout is a highly adaptive, dominant species and tends to take over natural habitats, forcing out other native species through competing for resources or preying upon competing species. Their behavior as a group tends to vary depending on their location with lake brown trout being shyer and less aggressive than river brown trout. When kept in captivity, the brown trout can be exceptionally aggressive when faced with cramped living quarters, so it is important to take adult size into consideration when building a habitat.


The brown trout survives in large part on insects as well as flies and shrimp. This is not a picky fish and it will eat whatever insect is populous. As they grow to maturity, the brown trout will also eat other fish including young brown trout and small creatures that fall into its habitat.

The brown trout eats mostly at night, however, when the climate becomes cooler, it will feed in the day as well.

The Rainbow Trout

The Rainbow Trout

Native Habitat

The rainbow trout is native to Asia and North America. In recent history, however, this salmonid was introduced to more than forty different countries for sports fishing as well as for food. As a non-native species, the rainbow trout has had a devastating effect on native fish in these areas; most commonly by feeding on them, competing for food, or passing on disease.


The rainbow trout measures on average, between 7” and 12” with the larger of the species being the male. The average lake dwelling rainbow trout grows to around 27 lbs., much smaller than the brown trout. In comparison, the stream-dwelling rainbow trout grows to only around 1lb. to 2lbs!


Rainbow trout have a somewhat olive-green coloration to them when looked at from above. Looking closely, however, will reveal a pearlescent purple tiny. Each of the sides of this fish is spotted with deep green and black spots. Unlike the brown trout, however, the rainbow trout has thick long bands of pink or white coloration down the center of each side.


The rainbow trout in their natural habitat has a life expectancy of between 3 and 4 years old. This fish reaches maturation at around 1 year old. The oldest rainbow trout known to date has been 11 years old, but this is an anomaly in most populations.


The rainbow trout differ from some of the other trout species in that they have an increased tendency to feed at the top of the water and to enjoy open water. This salmonid species is exceptionally sensitive to water quality as well as stressful environments. It is best for this fish to only be with other rainbow’s and the tank or pond must be adequately sized to accommodate all fish’s future size.


The rainbow trout is similar to most other trout species when it comes to diet. This fish feeds off surface-dwelling insects as well as other, smaller, fish. If a population becomes too dense for a specific area, the rainbow trout will also eat fish eggs or even plankton.

Keeping Trout in Captivity

Aquarium vs. Pond Trout

There are two methods of keeping trout in captivity – in an aquarium and in a pond. Both of these methods require a significant time and monetary commitment in order for the fish to remain healthy.

Keeping a Trout in an Aquarium

Trout in an Aquarium

Trout Aquarium Basics

The trout is a freshwater fish that prefers cooler waters, so the first thing to know is that any trout aquarium needs to be both freshwater and temperature controlled. It is also important that the in-home trout aquarium be spacious and replicate the natural habitat of the trout. The best way to replicate natural habitat in the trout aquarium is to have strong currents and plenty of aeration in fast moving water. Lastly, the trout aquarium must also offer consistent live food so that the fish can eat in a natural way. Failure to take any of these accommodations into consideration when setting up a trout aquarium will result in a failure to thrive and potentially result in the death of the fish.

Trout Aquarium Setup

When choosing an aquarium for a pet trout, perhaps the most important consideration is size. The optimal aquarium size for a trout is 1,000-gallons. Some smaller aquarists have been known to use 200-gallon aquariums, however, they are not optimal for a trout of any species to thrive. The optimal 1,000-gallon aquarium tank can house only 2 to 3 fish. Overcrowding the tank will cause a variety of problems including excessively dirty water, stunting the trout’s growth, and promoting aggression among the fish.

With the size requirement in hand, the next consideration for the trout aquarium is current. Trout naturally like to swim in waters with a strong current and high oxygen levels. This is achieved in an aquarium through fast moving water. Failure to create this fast-moving water for a trout will quickly deplete their oxygen level and cause them to become more susceptible to disease as well as decrease their activity level significantly. The best way to achieve the fast water movement needed by a trout is to utilize powerheads that are attached to an oxygenation system.

Trout Aquarium Setup

Tank size and water circulation and oxygenation aren’t the only considerations for a healthy aquarium trout. As a cold freshwater fish, the trout aquarium must have a chiller to maintain a water temperature of at least 59 degrees Fahrenheit. The best way to ensure that this temperature remains steady is to utilize a regulator.

In addition to a chiller, the trout aquarium, like any other aquarium, requires a high-powered filter. The most popular filtration method for aquarium setups like this is to utilize multiple filtration units with a sump system. It is particularly important to use enough filtration power for the tank size so that the water does not become oversaturated with waste. While a filtration system certainly keeps an aquarium healthy, it is also necessary to monitor feeding since too much food can quickly overpower the ability of even the best filtration system.

Lastly, the physical environment of the trout aquarium is just as important to the trout as filtration, aeration, and current. In order for an aquarium trout to thrive, it requires an atmosphere that is as close to nature as possible. For the brown trout, this environment means an aquarium with river rocks, greenery, tree roots, and larger rocks that can be used for shelter. For the rainbow trout, this environment means an aquarium with more free swimming space and fewer tree roots.

Setting up a Pond

Setting up a Pond
Ponds are another way to keep trout as pets and many of the same considerations that go into setting up a trout aquarium come into play here too.

It is still important to ensure that the captive trout have enough water to thrive, but when building a pond, it is also important to know that the bigger the pond, the harder it will be to cool. The temperature will still need to be controlled even with the outdoor pond and this can become a challenge in warmer climates. A good depth to consider for a trout pond that can be temperature controlled is around 9 feet. Again, the dimensions of the pond will depend on how many fish are going to be living in the pond, but the minimal requirements still apply. Also, keep in mind that the larger the pond (while still being within a manageable size for temperature control) the happier the fish will be.

In addition to keeping water cold, pond water must also have plenty of aeration and current. Without aeration the water in a pond will become oxygen depleted as depth increases, so a good aeration system is crucial. As with filtration of an aquarium, aeration must always be adequate for the size of the pond to ensure that water remains oxygen rich at all times. Adding aeration will also provide current to the water. Many trout pond owners also add water features such as fountains to create a more natural “stream” atmosphere with a current.

Another consideration when building a trout pond is filtration. Many people don’t know that ponds require filtration just like aquariums! Filtration helps to keep water clean and stops waste from building up – something that happens in any contained body of water! As with an aquarium, it is necessary to set up a filtration system that is optimized to the size of the pond. This ensures that water stays as clean as possible.

When it comes to feeding, ponds are easier to stock with live food for trout populations and the trout tend to thrive with such availability of varied food sources.

Lastly, the physical environment of the trout pond is just as important as it is in the trout aquarium. For both of these captive habitats, the aim is to replicate a natural environment to create stress-free conditions for the fish.



Feeding the pet trout requires a diet that mimics the diet of the trout in their natural habitat. This means a carnivorous diet that includes small fish as well as insects, shrimp, and worms. It is important to rotate food items to keep plenty of variation in diet as this ensures variation in nutrition. The best method of feeding these types of food is to purchase live food from a reputable source. Feeding dried food or “fish pellets” is not optimal for the trout since they are used to eating live prey.

One thing to keep in mind when feeding live prey is that even prey items can carry disease. Due to this potential for contamination, it is crucial that all food items be sourced through a reputable seller. This is important for both aquarium and pond kept trout.

Maintaining a Healthy Pet Trout

Maintaining a healthy trout in captivity can be challenging if all of the proper arrangements are not made. These arrangements include having a large, well-filtered, high current, highly oxygenated habitat that mimics that of the wild trout. This also means feeding optimal foods for the trout species and overall, monitoring of the trout’s appearance, activity level, and growth. Any signs of failure to thrive should be addressed immediately by checking all systems of the aquarium or pond as well as testing the water quality. Fish should also be checked for signs of parasites or illness.