Caring For Trout in Aquaponics Systems

We may earn compensation from the products mentioned in this post. See our Affiliate Disclaimer.

Over the years, trout have become increasingly popular amongst the aquaponics community due to their versatility both in the garden and on dinner plates. However, many newbie gardeners tend to shy away from the challenge of caring for trout in aquaponics systems because they believe maintaining the fish is just too difficult. In reality, the fish is relatively easy to maintain and a great species to leverage in your garden.

In this article, you will learn tips and tricks to help trout thrive in your aquaponics setup.

Why Choose Trout for Aquaponics Systems?

Trout are generally fast-growing freshwater fish types, allowing you to increase your fish population rather seamlessly. Besides having excellent flavor and texture, they can reach plate size much faster than other fish types. This becomes helpful if you want to harvest trout for personal consumption or if you plan to sell them.

In an aquaponics setup, the trout’s speedy population growth can also mean a rapid increase in your crop production. The fish can tolerate a range of temperatures, which is why they’re becoming a more preferred fish type to raise in aquaponic systems today.

Common Varieties of Trout

Many different varieties of trout exist, but three of the most well-known species are:

• Brook trout –also called speckled trout; the species is native to  Eastern North America in the US, as well as Canada, and they typically reside in cold water streams along the mountains
• Brown trout – this variety is also called European trout; it is native to Europe and western Asia but can be found in North America since their introduction to the region in 1883. They can be found in rivers and streams.
• Rainbow trout – populate the lakes and rivers of North America, west of the Rocky Mountains. This species does better at tolerating a variety of temperatures, so it’s a common type used in aquaponics systems.

Requirements For Raising Trout in Aquaponics

Here are some factors to consider when caring for trout in aquaponics systems:

Stocking density 

For a simple home aquaponics system, it is recommended to have a stocking density of 30-38 Liters of water per every 1 lb of fully-mature fish.

Tank size 

The optimal tank size for trout is 1000 gallons (3785 L). Some have successfully raised trout in 200-gallon tanks, but with supplemental aeration. What’s important to consider is that trout are active fish, which means they need a bigger space to move around. Overcrowding your tank will cause problems such as dirty water, stunted fish growth, and aggression interacting with other fish.   

pH level

Trout thrives at a pH level between 6.5 – 8.

Water temperature

Being a cool-water fish, trout prefer the cold, with optimum growing temperatures between 56 deg F and 62 deg F. They are able to tolerate as low as 38 deg F or as high as 75 deg F but this is not recommended for an extended length of time.

Fish diet/nutrient requirements 

Trout typically require a carnivorous diet, consisting of 40-50% of high-protein food sources such as fish meal and certain grains. However, the use of fishmeal has become less common over the years and has been replaced with cheaper alternative proteins like soy. 

Feeding frequency

At the start, you need to feed the fry at least 10 times a day. This gradually decreases to two to three times a day as the fish reach maturity.

It’s important to keep in mind that trout naturally have slower metabolisms than other fish since they are native to cooler waters. Due to this, you will want to ensure you don’t overfeed. Underfeeding is equally dangerous, so make sure you know how much to feed based on your tank size and number of trout.

How to clean the tank 

Algal blooms are common problems in aquaponics, but there are ways to clear your water of it and/or prevent their growth in the first place. One method is to put mechanical filters into your plumbing system. A cheap thin cloth acting as a barrier that covers the ends of the water pipes would suffice. The next step is to provide shade to prevent growth and buildup of algae. And the last option would be to get a fish that love to eat algae and let it do the job of cleaning your tank.

Common diseases

Parasite, bacterial, and fungal infections can happen, regardless if you have a small or large fish population. Most commonly, trout are afflicted with diseases when they live in stressful and unhealthy conditions. 

Furunculosis and fin rot are among the two common bacterial diseases found in trout. Furunculosis is usually treated with sulfamerazine and Terramycin while fin rot is remedied by a copper sulfate solution. There are also external parasites that cling to the skin of the fish. In this case, a formaldehyde bath (some have done salt bath) may be given to an isolated group of fish before being returned to join the general population.

Oxygen requirements 

Trout need higher levels of dissolved oxygen compared to other fish types, like perch or tilapia. It is recommended for a trout tank to have up to 7.0 ppm of oxygen levels to keep the fish happy and healthy.

Best Trout Species for Aquaponics

The rainbow trout is the best one to use for aquaponics. Not only do they look pretty, but they are generally hardy species, making aquaponics farming rather easy.

Best Suited Aquaponic Plants

Trout is best for cool-growing crops, such as those that belong to the Brassica oleracea (cabbage, broccoli, collard greens).

Restocking

It only takes a year for a male trout to mature, so restocking should be done every two to five years. The frequency of restocking will also depend on whether you have non-sterile fish and sterile fish, or if you consume the fish from your tank on a regular basis.

Filtration System

When caring for trout in aquaponics systems, monitoring the ammonia-nitrite and nitrate levels is essential to maintain a healthy aquaponics environment for the fish. Biofiltration is a recommended filtration system for trout care.

Sunlight 

Studies have proven that trout embryos are killed when exposed to direct sunlight, even for just a few minutes at a time.

Can They Be Mixed With Other Fish?

Trout are generally a dominant species and tend to exhibit territorial behavior. Some have mixed trout with other freshwater species like Silver Perch without problems, as long as they are of the same size. Adding juveniles to the bigger fish, however, won’t be a good idea as they could get eaten.

Breeding 

Milt is collected from the male, while females are stripped for their eggs. It is recommended that milt should come from more than one male to ensure fertilization. The milt will then be mixed with the eggs. Water is added to the mixture to activate the sperm, so fertilization can begin. Once fertilized, the eggs are ready for transport 20 minutes after and should be done within 48 hours. Direct sunlight should be avoided at all costs for embryos to survive.