Getting Started With Aquaponics. What Are The Best Fish To Raise? 

Fish are one of the main components of an aquaponics system and play a vital role in your system as they will be the source of natural fertilizer for the plants. 

Fish provide food and fertilizer for your plants, so it is important to plan which types of plants you want to grow and pair them with the right type of fish species.

Certain fish and plants thrive at specific temperatures, so it is essential to carefully select the fish to raise in your aquaponics system to make sure that both fish and plants will be successful in the given water conditions.

There are many types of fish that you can raise in your system, depending on your local climate and fish availability in your area. Large, small, edible, or decorative, there are many options to suit your needs. However, not all fish can be used in an aquaponics system, so you must choose fish species that will survive and thrive in your system. 

What to Consider When Choosing Your Fish 

Are the fish you are raising for home-use, commercial use, or recreational use? Besides providing nutrients to the plants, it is important to know and plan out the purpose of the fish in your system. Here are some key things to consider in selecting the best fish for your aquaponics system. 

1. Temperature

Some fish thrive in cold water, while some thrive in warm water. So the first thing you should consider is; Is the fish your planning to grow capable of surviving within the temperature range of your location? Fish thrive at specific temperatures, so you need to know the climate of the place where you will place your fish tank and how quickly temperature changes from day tonight. Knowing the temperature changes and the temperature preference of the fish you want to raise will help you choose the best fish for your aquaponics system.

2. Fish availability in your location

The next important thing to consider is fish availability in your location. Some fish are available only in some areas, an example is the Barramundi, this fish is not easily available in the US but is readily available in Australia. The ease of acquiring fingerlings also matters in selecting the best fish best to raise in your aquaponics system. Tilapia is the most common fish species that are used in aquaponics because they are readily available in most parts of the world. 

3. What fish is legal in your location?

Not all fish are legal to be purchased and grown in some locations. So it is essential to check first with your local fish farming laws to make sure that the fish you intend to use in your aquaponics system is legal in your location.

4. Fish Type and Maintenance Difficulty

Some fish are hardy and need little care, while others are sensitive and costly to raise. Choose a hardy fish that is immune to diseases and parasites, if you don’t want to spend a lot of time and effort maintaining your system. Tilapia and Koi are hardy fish and great for beginners in aquaponics. Trout require a higher standard in terms of water quality.

5. Size and Space Requirements

Make sure to know the adult size of the fish that you are planning to raise and the size of the tank needed. The available space in your fish tank will determine what type and amount of fish are suitable for your system. Some fish need space to thrive, so be aware of the maximum adult size of the fish you are planning to raise. For example, channel catfish grows up to 40-50 lbs so they need a large fish tank of at least 250 plus gallon. Koi also requires large fish tanks or large ponds to thrive while cods are only suitable on high-density tanks to suppress their territorial behavior.

6. Filtration Capacity

The filtration capacity of the media bed in your aquaponics system determines how many fish you can keep in your fish tank. You need to balance fish needs and the capacity of the plants and not over-populate or under-populate the fish as an overcrowded fish tank can disrupt the oxygen level in the water. As a general rule of thumb, you should have 1-inch of fish length per gallon of water.

7. Fish Diet

Fish diets are one of the important things to consider in fish selection for your aquaponics system. As fish food choice and fish food nutrient availability can affect the maintenance cost of your system.

Fish are classified into four groups based on their feeding patterns. These groups are Herbivores, Carnivores, Omnivores, and Detritivores.

Herbivorous fish eats plants, fruits, and algae. They have a special intestine that is designed to break down plant matters, and they need more frequent feedings as they don’t have a stomach to hold large volumes of food. 

Omnivorous fish eat both vegetables and meat except for some grains and plants that they cannot digest. They are excellent fish to raise because they are easy to feed. Omnivorous fish also eat live foods as well as flakes.

Carnivorous fish are the live food and meat-eaters. They have large mouths and sharp pointed teeth that can grasp and tear their prey. Carnivorous fish also have a large stomach and can swallow their food without chewing. They are not good fish to raise with other fish in the same tank because they will eat other fish.

8. Breeding Habits 

Fish breeding habits are also important in selecting fish to raise in your aquaponics system. Some fish species don’t reproduce in captivity while other fish species like tilapia reproduce easily and quickly. Sometimes fast reproducing fish species can create problems in poorly built systems and can cause fish stocking density problems. You may need to have separate tanks for breeding fish to spawn and keep the young fish alive and healthy. 

The Best Fish to Use In Your Aquaponics System

Tilapia      

Aside from being tasty and adaptable to many culinary styles, Tilapia can adapt to their environment and withstand less than ideal water conditions, making them one of the best fish to raise in aquaponics. Tilapia is a hardy fish and has a diverse diet, they can survive on insects, algae, and worms. Harvest time for Tilapia is between six and eight months but as long as 15 months, depending on how warm the water is, how much they are fed, and the size of fish that you want to harvest. Tilapia prefer a temperature of 82 - 86 °F and a pH of 6.5 - 9. 

Advantages of Tilapia

• Fast growth rate ( about nine months from fingerling to harvest ).
• Hardy fish and can adapt to their environment.
• Great for eating, it has a good flavor.
• Ability to reproduce quickly.
• They have an omnivorous diet ( they don’t eat other fish ).
• They don’t require lots of dissolved oxygen. 
• Top feeders, you can assess their consumption easily and adjust accordingly. 

Disadvantages of Tilapia

• They require warmer water above 55 °F.
• Their ability to reproduce quickly can be an issue if you have a small aquaponics system, but there are ways to counteract this. 
• You always need to keep your water warm in a colder climate.

Trout     

Trout are the perfect fish for indoor and outdoor systems because they have an excellent temperature range. Trout prefer colder water and thrive in temperatures ranging from 56 - 68 °F making them ideal for a cooler environment. Trout grow slowly and reach about one pound in 4 years in the wild.

Advantages of Trout

• Good tasting fish to eat and loaded with protein and omega fatty acid.
• Ideal in colder climates.
• Feed on a variety of diets, which includes fish, insects, and soft-bodied invertebrates.

Disadvantages of Trout

• Slow growth rate.
• Can’t be kept with other fish.
• It needs plenty of space to ensure their proper growth.
• Require clean filtered water to live.
• Fewer plant choices due to their cooler water requirement.
• Close monitoring of their pH level is important.
• Need high dissolved oxygen levels in the water (minimum 10 mg/liter). 

Catfish     

Catfish are one of the best-farmed fish and are popular for their taste. Catfish are bottom feeders and valuable scavengers that can withstand a wide range of water conditions. They are not territorial and easy to breed and raise. Catfish thrive at a similar temperature to tilapia 75 - 85 °F and require a pH of 7 -8. They grow relatively fast and can be harvested within three months.

Advantages of Catfish

• Non-territorial (can be raised with other equal-sized fish).
• It can tolerate different water temperatures.
• Good tasting fish for eating.
• Feed on a variety of plants, bugs, small fish, and pellets.
• Easy to raise and breed. 

Disadvantage of Catfish

• They require high protein food.
• Catfish do not have scales and are easily stressed or injured when they’re not handled properly.
• They are sensitive to water quality, water temperature, and pH.  

Bass     

There are many kinds of bass to choose from. Aside from being delicious, the bass is a hardy fish that can handle low water temperatures, making them a great option if you live in a colder climate. Bass thrive in a water temperature of 65 - 80 °F and pH of 6 - 8. Bass can be harvested within one year from fingerlings.

Types of Bass

• Large-mouth bass
• Smallmouth
• Hybrid striped
• Australian
• White bass 

Advantages of Bass

• Top feeders, you can assess their consumption easily and adjust accordingly.
• Bass eat almost anything, insects, worms, and pellets.
• Don’t need a lot of protein, giving you more food choices when feeding them.
• Great-tasting fish to eat.

Disadvantages of Bass

• Potassium levels need to be monitored as changes in this can make your bass ill.
• Conditions must be monitored closely to ensure clean water, proper oxygen, and pH levels.
• Do not tolerate bright light and poor feeding.

Salmon     

Salmon are a great-tasting and healthy fish to raise in your aquaponics system. They require a large fish tank to thrive and take about two years to reach full size before harvesting. The water temperature for salmon should be between 55 - 65 °F and a pH range of 7 - 8. 

Advantages of Salmon

• Salmon are social fish, tolerant and friendly with other fish.
• High tolerance to cold conditions.
• Delicious and healthy to eat. 

Disadvantages of Salmon

• They require more food than other fish.
• Are more likely to contract diseases than many other types of fish.

Koi     

Koi is one of the most popular ornamental fish used in aquaponics. Koi have a long lifespan and can breed and live comfortably within the aquaponic system. Koi can survive off of many types of food and are also disease and parasite resistant. They thrive on temperatures of 65 - 78 °F and pH level of 6.5 - 8. 

Advantages of Koi

• Disease and parasite resistant.
• It can survive in a wide range of temperatures.
• Ornamental and attractive fish.
• Long lifespan.

 Disadvantages of Koi

• Not a good fish for eating.
• It can produce excess waste as they age and will require more cleaning to keep your system healthy.

Goldfish     

Goldfish is an excellent ornamental fish for aquaponics that is easy to take care of. They are a tough fish species that can live in a high level of water pollution. Goldfish prefer temperatures of 78 - 82 °F and prefer a pH range between 6 - 8. Because of their small size and parasitic nature, goldfish are not edible.

Advantages of Goldfish

• Beautiful ornamental fish.
• Hardy fish and tolerant of pH changes.
• It can live in polluted water.
• Produce lots of beneficial waste nutrients for the plants.

• Can’t mix with other fish in one tank.
• Not edible.

Fish Care

Fish highly depend on the water in which they live, so changes in the water will have a direct effect on their health and well-being. These changes are often invisible to the eye, as well as monitoring their color and behavior. It is also important to test the water regularly 

• Cloudy or swollen eyes.
• Rapid movement of the gills.
• Distended or hollow stomach.
• Opaque, clamped, or frayed fins.
• Wounds, fungus growth, patches or spots of cloudy white/grey, or color changes in the skin. 
• Unusual behavior. (unusual swimming patterns, darting around the tank in an alarmed fashion, hanging at the surface or hiding away and being unusually shy)

Causes of Fish Disease

Diseases can be introduced by a new fish, plants, live food, invertebrates, or equipment used in the system. There should be a delicate balance in the fish tank to ensure that the fish remain healthy. Like all animals, fish carry bacteria, viruses, fungus, and parasites. Not all of these are harmful, but some of these microorganisms called pathogens have the potential to cause diseases. The following factors can cause fish disease.

• Environment or poor water quality.
• Not getting along with other fish in the fish tank.
• Poor or unbalanced diet.
• Fish Stress.

How to Prevent Fish Diseases

1. Quarantine new fish in a separate fish tank for two weeks before introducing them into an established fish tank. 
2. Feed the fish with a good, varied, and a well-balanced diet.
3. Keep the water quality in your system clean, including cleaning of the filter if you have one fitted to your system.
4. Ensure the system is within the parameters for pH, ammonia, nitrites, and nitrates for your particular fish.
5. Add extra aeration. You can rarely have too much aeration.
6. Reduce the frequency of opening and closing the lid on the tank and minimize scooping fish out to inspect them. 
7. Treat the disease as soon as it is identified.

Conclusion

It is essential to choose the right fish for a successful aquaponics system. But it is also necessary to establish a maintenance routine to prevent diseases of your fish and plants. Feed your fish the right food, not just for their health but also yours if you plan on harvesting and eating them. Healthy fish playing in their tank are interesting to watch, and may even become your pet!

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