How to Raise Rainbow Trout in Aquaponics

In Aquaponic Aquatic by Aquaponic GuruLeave a Comment

Rainbow trout do well in an aquaponics system, especially in a colder climate are preferred environmental conditions, oxygen level, diet and more tips for trout.

In aquaponics rainbow trout like oxygen levels of 5.5ppm, they are also carnivorous eaters.

Any time when the water for trout goes above 77 degrees we are looking at an aquaponics apocalypse.

In this article, we’ll be discussing the rainbow trout, their preferred environmental conditions.

Also, as well as how you can best fit them into your aquaponics set up.

If your local temperatures are far below the comfort level, you may want to take a second look at the rainbow trout.

Though they can be a bit picky about their water quality, this species is valuable for its role as a sport fish and a culinary delight.

They’re also one of the most beautiful fish you can raise and grow fairly quickly in the right aquaponics setup.

Rainbow Trout Thrive in Cooler Temperatures

The rainbow trout is a fish that prefers the cold waters of mountain lakes and streams.

They don’t do well in the heat but thrive between 50 and 60 degrees Fahrenheit.

They can and do live in colder waters, but tend to stop eating, and therefore cease growing, at around 40 degrees.

Still, when you compare them to heat-loving tilapia, they make a superior choice for the colder climate grower.

They also make an excellent choice for someone looking to grow crops over the winter.

With a double layer of plastic over your greenhouse, it’s easy to keep things warm enough for rainbow trout to fertilize a winter crop.

The water of your tanks will act as a heating pad, trapping the energy of the sun and radiating it through your greenhouse during the night.

Black rocks or plastic covered sand over the unplanted ground can also hold and release heat when your natural source has gone down.

This allows the industrious grower to significantly extend their season.

Rainbow Trout Taste is Highly Valued

Beyond their benefits to the winter grower, the best part about rainbow trout is that taste great.

The subtle, nutty flavor of their meat lends itself well to simple, light dishes.

This means that surplus can be sold to restaurants and individuals once you’ve obtained the proper licensing.

Be sure to check with your local offices to make sure you’ve got all your ducks, or in this case, fish in a row before you start advertising.

That also means that if you have a big enough setup, a breeding operation could prove as profitable as the vegetable crops your fish fertilize.

A hundred 3 to 5-inch trout fingerlings can cost as much as $160, and the price only goes up from there.

Low-Stock Density in Fast Moving Waters

This is a fish that makes its home in typically fast-moving waters where other species tend to have a harder time.

They don’t do well with dirty water, so stocking at around 10 to 20 gallons of water per pound of fish is a fairly safe bet.

That means if you have a 300-gallon tank and want to grow your fish for to a couple of pounds in size.

Realistically you should have 15 to 30 fish in each tank.

The more your water is moving, the more oxygen is in the water, and the higher the density you can stock at.

This is a fish where a biofilter or even multiple biofilters is almost always recommended to keep your water clean and moving.

Rainbow Trout like a lot of oxygen level and not a lot of muck, so using a moving biofiltration system often works out well.

Adding an air stone to your system as it begins to get hotter can also prove quite helpful to your fish.

Rainbow Trout are Steady Growers

Rainbow trout are one of the few fish that hold a candle to the rapid growth of the mighty tilapia.

With good water quality, ideal temperatures, and a heavy protein diet, rainbow trout can easily grow to plate size in just 9 to 12 months.

By the 9 month mark, you can expect each fish to weigh at least a pound.

If allowed to continue to grow an additional three months, you’ll find many individuals will weigh two pounds or over.

It might not be the 6 to 9 months it takes for tilapia.

Trout are better than the 16 to 24 months for largemouth bass or the insanely slow growth of the goldfish.

Finally, the rainbow trout makes perfect sense for an aquaponics system.

Trout Can Be Difficult to Breed in heat; that’s why you need fish tank coolers.

The largest drawback with rainbow trout comes if you’re thinking of breeding them.

Taking on such a venture requires a significant amount of space.

Adult rainbow trout can weigh anywhere from 5 to 20 pounds depending on the lines you’re working with.

The females can lay around 2000 eggs each, and one male can fertilize several female’s eggs.

But they can be difficult to nearly impossible to get to breed on their own in captivity.

So both the hens and bucks are often manually manipulated to squeeze out a row and spawn.

Eggs are then usually dry fertilized through a process where the harvested row is mixed with the male spawn in tubs.

This “dry” mixture is then placed in hatching troughs.

Combined with their heat sensitivity, this makes breeding the rainbow trout a venture for those with a lot of space, time, and an eye for detail.

Correct Amount of Aeration for Rainbow Trout an Adequate Oxygen Level

Unlike koi or catfish, rainbow trout need a constant oxygen level of 5.5ppm to grow at peak efficiency.

In fact, one of the reasons why they begin to struggle as the water temperature rises is that hotter water burns off oxygen faster than cold water.

To avoid this problem and give your rainbow trout a little leg up in the summer months, consider adding an air stone into your system.

Using a moving biofilter as opposed to a drip style, one can also help in adding a bit more air to your water.

Another way to help keep the air concentration in your system a little more constant is to build your grow beds higher than your fish tanks.

The process of the water falling into the tank saves you money.

You do not have to pump water back into the fish while adding flow and, therefore, air into the tank.

If you choose to build your beds over your fish, make sure to raise them enough that the trout can’t nibble your roots.

While it’s fine for your fish, your plants may suffer.

You can always buy a 2-in-1 aeration and fish tank cooler if you are limited space.

Rainbow Trout High Protein ‘No Carb’ Diet

Unlike tilapia, rainbow trout have a carnivorous diet.

Whether you choose homemade food or go with a reliable quality pellet, take care to pick a diet, with 40 to 50 percent protein and 18 to 20 percent fat.

This fish does well with at least supplemental feedings of insects and mollusks.

If at all possible, avoid corn, wheat, and soy as major ingredients.

Are you interested in a homemade fish food recipe? Check out our fish food recipe we use to ensure a highly sustainable growth rate.

In a perfect world, your fish would be fed four times a day, with the total amount reaching 2 to 3 percent of their body weight.

So if you have 30 fish at a pound each, you’ll want to feed 68 to 102 grams of food, four times a day for a total of .6 to .9 pounds.

Feeding several times a day cuts down on waste while maximizing the amount of fertilizer your fish will produce.

Not only does this help the quality of your water, it means that both your fish and your plants will grow bigger faster.

Icy Summers With our Recommended Fish Tank Cooler

The rainbow trout is a cold hardy fish who can thrive in water temperatures that many of the common species used in aquaponics would never survive.

That said, they don’t like heat.

These fish are most comfortable at around 60 Fahrenheit.

The highest temperature they can live in is about 70. At 73, they become stressed.

By 77 degrees Fahrenheit, they stop eating and quickly begin to die off.

Fish tank coolers can be expensive! Check out our recommended gear. Don’t waste your money on useless equipment.

A carefully insulated tank with plenty of shade and well-circulated water should help keep your fish at the right temperature.

But what you do if your trout are outside in an open water source like a pond and temperatures begin to rise?

You can’t air condition the outside, so instead try throwing some ice into your water to keep your stock cool enough to keep growing.

Avoid putting ice directly in the water. Placing ice in a bag that will float will provide a gentle decline of temperature.

Adding to much ice can shock your fish. This is a dangerous method, but it can work.

The best bet is to never let the water get any other than 70 degrees. So staying on top of the temperature water is vital!

In the middle of the day during summer time, you might have a hard time keeping a steady temperature depending on your climate.

If this sounds like to much work then read our article we have written about different fish tank chillers.

Please note: When you are at work in the middle of the day, the temperatures might rise.

Rainbow trout in aquaponics relay on fish tank coolers.

From our experience, we have put together a list of the best fish for aquaponics. Before you seal the deal on Rainbow Trout check out our purchaser guide for aquaponic fish.


In conclusion, the rainbow trout is a priced fish across the world both for their beauty and their amazing taste.

They’re highly marketable, but a bit slower to grow than some other commonly used species of the aquaponics world.

They thrive in somewhat low densities and like cooler temperatures.

Rainbow Trout may need additional help to stay cool in the summer and enjoy a high quality, high protein diet.

If you’ve got the space and you live somewhere cold, consider using the profitable rainbow trout for your soilless growing system.

We will be happy to hear what you have to say!

This site uses Akismet to reduce spam. Learn how your comment data is processed.