One of the most important decisions you will have to make if you want to start your own aquaponics system is which fish species to use. In an aquaponics system, fish plays a critical role as it produces the natural fertilizers needed by the plants to thrive.
Aquaponics allows you to raise a wide variety of fish species. However, to be successful, you must carefully choose the best aquaponics fish species that will survive and thrive in your system. This article will look at the best fish to raise in aquaponics systems.
What To Consider When Choosing Your Fish
To build a successful aquaponics system, you'll need to carefully select the fish that will thrive in your climate and location. Different fish species require different water temperatures and pH levels. So it is essential to consider the factors below in choosing the best aquaponics fish for your aquaponics system.
Edible vs. Ornamental Fish
Fish edibility will play a significant consideration in your fish selection. If you're planning to eat your fish, you need to build your system around edible fish species like tilapia, catfish, carp, largemouth bass, etc. You can eat these edible fish species, but often, they are more challenging to maintain and require specific conditions.
Ornamental fish species like goldfish and koi are easier to maintain, more resistant to diseases and parasites, and less expensive. Small ornamental fish species, like angelfish, tetras, and danios, are great for indoor aquaponics systems.
Fish are cold-blooded species, and their ability to adjust to an extensive range of water temperature is low. Some fish thrive in cold water, while some thrive in warm water. So the first thing you should consider is if the fish you're planning to grow can survive in your location's temperature range?
Fish thrive at specific temperatures, and a steady temperature within their correct tolerance range keeps the fish healthy and helps them grow faster. Knowing the water temperature changes and the preference of the fish you want to raise will help you choose the best fish for your aquaponics system.
Fish Availability in Your Location
Another essential thing to consider is the fish availability in your location. Some fish are available only in some areas; an example 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 to raise. Tilapia and goldfish are the most common fish species used in aquaponics because they are readily available in most parts of the world.
What Fish is Legal to Raise 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 ensure that the fish you intend to use in your aquaponics system is legal in your location.
Fish Type and Maintenance Difficulty
Some fish species are hardy and easy to raise, while others are sensitive and costly to grow. If you don't want to spend much time and effort maintaining your system, choose a hardy fish immune to diseases and parasites. Tilapia, goldfish, and Koi are hardy fish and great for beginners in aquaponics.
Size and Space Requirements
The size of your fish tank will determine what type and amount of fish are suitable for your system. Some fish require space to thrive, so be aware of the maximum adult size of the fish you plan to raise to provide your fish with the right size fish tank. For example, a channel catfish can grow up to 40-50 lbs, so they need a large fish tank of 250 plus gallons.
The filtration capacity of your aquaponics system determines how many fish you can keep in your fish tank. It would help balance the fish's needs and the plant's capacity and not over-populate or under-populate the fish. An overcrowded fish tank can disrupt the oxygen level in the water. As a general rule of thumb, you should have a 1-inch fish length per gallon of water.
Fish breeding habits are also one factor in selecting fish to raise in your aquaponics system. Some fish species don't reproduce in captivity, while others, like tilapia, reproduce easily and quickly. Sometimes fast, producing fish species can create problems in small or poorly built systems and 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.
Fish diets are one of the essential things to consider in fish selection for your aquaponics system. Fish requires the correct balance of proteins, fats, carbohydrates, vitamins, fats, and minerals to thrive and give plants the proper nutrients needed for their growth. Your fish food choice and fish food nutrient availability can affect the maintenance cost of your system.
Commercial feed pellets are highly recommended for small-scale aquaponics systems, especially at the beginning. You can also feed alternative or homemade fish food to your fish. Still, it would be best if you gave special attention because sometimes they are not balanced in the essential nutritional components needed by the fish.
Water Quality For the Fish
Ammonia and nitrite are toxic to fish. Ammonia and nitrite are considered harmful when the levels are above 1 mg/liter, although any level of these compounds can contribute to fish stress and other fish diseases.
Fish can tolerate a wide range of pH but thrive at levels of 6.5-8.5. A substantial change in pH levels in a short period can cause problems for the fish. So it is essential to keep the pH stable.
Dissolved oxygen (DO) is necessary for growing fish and beneficial bacteria that convert fish waste into plant nutrients. It is recommended that the DO levels in aquaponics systems should be maintained at 5ppm or higher. If the DO levels in your system are too low, increase aeration by using a larger pump or adding air stones. Also, do not overstock the fish in your system to avoid low levels of DO.
Light and Darkness
Reduce the light level in the fish tank to prevent algae growth, but it should not be completely dark, as fish will experience stress and fear when a completely dark fish tank is exposed to a sudden light when uncovered. The ideal light is indirect natural light through shading, which will prevent algae growth and fish stress.
Fish Selection for Aquaponics System
Ideal pH Range: 6.5 - 9.
Ideal Temperature Range: 82 - 86 °F
Ideal Fish Tank Size: A fully grown tilapia will weigh 1 pound, although they can grow larger. The rule of thumb is that one pound of tilapia will need 3 gallons of water. So this means that in every 3 to 5 gallons of water, only raise one tilapia.
Food Requirements: Tilapia are omnivore fish species that eats plant and animal-based feed. In aquaponics, you can also feed with leftover vegetables and other alternative or homemade fish food.
Tilapia is one of the best fish to raise in aquaponics because they are hardy and can adapt to their environment and withstand less than ideal water conditions. They are resistant to many pathogens and parasites and in handling stress.
The harvest time for Tilapia is between six and eight months, depending on how warm the water is, how much they are fed, and the size of fish you want to harvest. Tilapias are easy to breed in small-scale and medium-scale aquaponic systems. If you’re looking to purchase tilapia fingerlings, click here.
We Offer Two Types of Tilapia For Sale
Advantages of Raising Tilapia in Aquaponics:
- Tilapia has a faster growth rate (about nine months from fingerling to harvest).
- Tilapia is a hardy fish and can quickly adapt to its environment.
- They are edible and taste great.
- Ability to reproduce quickly.
- They have an omnivorous diet, meaning you can feed with alternative fish food.
- They are top feeders. You can assess their consumption quickly and adjust accordingly.
Disadvantages of Raising Tilapia in Aquaponics:
- 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.
Rainbow trout is ideal for aquaponics in colder or temperate regions as they can tolerate colder climates. They have a very high tolerance to salinity and can survive in freshwater, brackish water, and other marine environments.
Advantages of Trout:
- Rainbow trout tastes good and is loaded with protein and omega fatty acids.
- Trouts are ideal in colder climates.
- They feed on various diets, including fish, insects, and soft-bodied invertebrates.
Disadvantages of Trout:
- Slow growth rate.
- They can't be kept with other fish.
- They need plenty of space to ensure their proper growth.
- Require clean filtered water to live.
- Fewer plant choices because of their cooler water requirement.
- Close monitoring of their pH level is essential.
- Need high dissolved oxygen levels in the water (minimum 10 mg/liter).
Catfish are the easiest species for beginners or aquaponics growers who want to grow fish with an unreliable electrical supply. Given the high tolerance to low DO and ammonia levels, catfish can be stocked at higher densities and provided adequate mechanical filtration.
Catfish are benthic fish, meaning they are bottom feeders and valuable scavengers that are not territorial and easy to breed and raise. They grow relatively fast and can be harvested within three months.
When raising catfish, it is recommended to use a tank with more significant horizontal than vertical space to allow the fish to spread out at the bottom. You can also raise fish like tilapia, perch, or bluegill sunfish with catfish in the tank.
Advantages of Catfish:
- Non-territorial (can be raised with other equal-sized fish).
- They can tolerate different water temperatures.
- Good tasting fish for eating.
- Feed on various plants, bugs, small fish, and pellets.
- Easy to raise and breed.
Disadvantages of Catfish:
- They require high protein food.
- Catfish do not have scales and are easily stressed or injured when not handled properly.
Largemouth bass can tolerate various temperatures, low DO, and pH. However, largemouth bass prefers clean water. They are carnivorous fish, and they require a high protein diet. Largemouth bass's growth rates depend on the temperature and feed quality.
Most of the growth is obtained during the warmer season in temperate climates. Because of their high DO tolerance and resistance to elevated nitrite levels, largemouth bass is one of the best fish to raise for aquaponics farmers, particularly those who cannot change fish species between cold and warm seasons.
Advantages of Largemouth Bass:
- Bass are top feeders.
- Bass eat almost anything like insects, worms, and pellets.
- They don't need much protein, giving you more food choices when feeding them.
- Great-tasting fish to eat.
Disadvantages of Largemouth Bass:
- The potassium levels of Bass need to be monitored as changes in this can make them ill.
- Their conditions must be monitored closely to ensure clean water, correct oxygen, and pH levels.
- Bass do not tolerate bright light and have poor feeding habits.
Advantages of Salmon:
- Delicious and healthy to eat. Salmon are social fish, tolerant and friendly with other fish.
- Salmon has a high tolerance for cold conditions.
Disadvantages of Salmon:
- They require more food than other fish.
- Salmon are more likely to contact diseases than many other fish species.
Ideal Temperature Range:65°F - 78 °F
Ideal Fish Tank Size: A 1000-gallon tank will be enough to have 6-5 koi. They are also ideally grown on ponds.
Koi is one of the most popular ornamental fish used in aquaponics. Koi has a long lifespan and can breed and live comfortably within the aquaponic system. Koi can survive off many food types and are disease- and parasite-resistant.
Advantages of Koi:
- Disease and parasite resistance.
- It can survive in a wide range of temperatures.
- Ornamental and attractive fish.
- Long lifespan.
Disadvantages of Koi:
- Not a good fish for eating.
- Needs a larger fish tank.
- It can produce excess waste as they age and require more cleaning to keep your system healthy.
- 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.
- You can't mix them with other fish in one tank.
- Not edible.
Fish Care in Aquaponics Systems
Acclimating the Fish
In adding fish to the system, it is essential to acclimatize the fish first, to remove the stressful factors that can cause death to the new fish. The two simple ways of acclimating your fish are:
- Keep the new fish in a small aerated container with their original water and slowly add water from the fish tank over a day.
- Slowly allowing the temperature to equilibrate by floating the sealed transportation bags containing the fish in the fish tank for at least 15 minutes. Then slowly add a small amount of fish tank water to the transportation bag.
The fish feed ratio provides a way to balance the components of an aquaponics system. Fish feed rates vary according to the growth stage of the fish.
- During the grow-out stages, the recommended fish feeding rate is 1 to 2 percent of their body weight per day. So, if the fish stocking density is 10 to 20 kg per 264 gallons, you must provide 200 g of fish feed per day.
- During the first two to three months, small fish (like 50 g tilapia fingerling) eat about 3 percent of their body weight per day. So if you have an initial stocking of 40 fingerlings and weigh 2000 g together, they will consume approximately 60 g of fish feed per day.
- After two to three months, the feeding rate will be 80 to 100 g of fish feed per day. (It is because the 40 fingerlings will have grown to 80 to 100 g each, and the total weight will be 3200 to 4000 g)
Fish Health and Behavior
The primary indicator of fish health in your aquaponics system is their behavior. It is essential to recognize the behavior of your fish and look for signs of fish stress, disease, and parasites to maintain healthy fish.
Here are some important ways of maintaining healthy fish in your aquaponics system:
1. Observe fish before and after their daily feeding and note how much feed is eaten.
2. Observe and take notes of the fish's behavior and appearance daily.
3. Understand the signs of fish stress, disease, and parasites.
4. Maintain a low-stress environment with consistent good water quality, specific for the fish in the system.
5. Maintain the correct water temperature suited for the fish in the tank.
6. Use the proper stocking density and feeding rates.
Healthy Fish Behavior
Healthy fish in your system shows the following behavior:
1. Extended fins and straight tails.
2. A graceful pattern of swimming. No lethargy. However, catfish often sleep at the bottom of the fish tank until they wake up and begin feeding.
3. A healthy appetite and not shying away at the presence of the feeder.
4. No marks, discolored blotches, streaks, or lines.
5. Not rubbing or scraping on the sides of the fish tank.
6. Sharp, clear, and shiny eyes.
Several conditions can cause fish health problems in your aquaponics system: fish disease, parasites, fungus, and bacteria. These can all appear in your fish tank and quickly spread disastrous effects on the fish. The chance of fish disease or stress is incredibly high when you introduce new fish or add fresh water to your system, as the new fish might have brought diseases with them.
Prevention is the best way to prevent disease in fish, and recognizing the signs of fish diseases can help you avoid the loss of fish in your aquaponics system. In preventing fish disease, it is essential to check your fish regularly for any of the following signs:
- Check their appearance regularly because several parasitic and fungal infections can be visible on the fish skin, scales, or fins.
Most external signs of disease are:1. Ulcers on the body surface, discolored patches, and white or black spots.
2. Fin rot, ragged fins, or exposed fin rays.
3. Abnormal body configuration, twisted spine, and deformed claws.
4. Swollen appearance and cotton-like lesions on the body.
5. Exophthalmia or swollen popped eyes.
- Check for behavior changes, such as your fish becoming lethargic, refusing to eat or changing feeding habits, changing swimming patterns, odd position in water, head or tail down, difficulty maintaining buoyancy, and fish gasping at the surface.
- If your fish looks bloated or their scales seem raised, it also indicates health concerns.
Causes of Fish Disease
Fish diseases can be introduced by adding new fish, poor water quality, live food, invertebrates, or equipment used in the system. Like other animals, fish also carry bacteria, viruses, fungus, and parasites. Though not all these bacteria are harmful, some of these microorganisms, called pathogens, can potentially cause fish diseases.
The following factors can cause fish disease in your aquaponics system.
- Adding new fish to the system
- Environment or poor water quality
- Fish stress
- A poor or unbalanced diet
- The equipment used in the system is not suitable for the fish
- Not getting along with other fish species in the fish tank
Symptoms of diseases to look out for:
- 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)
How to Prevent Fish Diseases
- Purchase healthy fish seeds from a reputable and reliable hatchery.
- Never add unhealthy fish to the system. Examine and quarantine new fish in a separate tank for two weeks before introducing them into an established fish tank.
- Feed the fish with a good, varied, and well-balanced diet.
- Keep the water quality in your system clean, including cleaning the filter if you have one fitted to your system.
- Ensure the system is within the parameters of pH, ammonia, nitrites, and nitrates for your particular fish.
- Add extra aeration. You can rarely have too much aeration.
- Reduce the frequency of opening and closing the lid on the tank and minimize scooping fish out to inspect them.
- Treat the disease as soon as it is identified.
Conclusion: On the Best Fish for Aquaponics
The fish species mentioned above are the best fish for aquaponics systems. However, choosing the best aquaponic fish species in aquaponics is not enough; managing your system correctly is also essential. A proper management practice will help keep your fish happy and healthy. Hopefully, this article enables you to make choosing the best fish for your system quicker and more enjoyable.
February 08, 2022
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