Numerous species of catfish are found on our planet. The North American catfish family alone has 45 species. Similar to the other aquaponics fish, identifying the selection of catfish available for you is very important. In this section, I have shortlisted three types of catfish that may do well in your chosen aquaponics setup.
Eel tailed catfish
With the scientific name of Tandanus tandanus, the eel-tailed catfish is a popular choice for aquaponics. They are omnivorous bottom feeders who can be given both sinking pellets and live food like earthworms. These catfish can be reddish red, olive green, or brownish-purple in color when fully grown. Young fish have a mottled black and grey appearance. The pectoral and dorsal fins of the tandanus are covered in enormous spines, and four pairs of sensitive barbells enclose their mouth.
Growth rate: 1 pound within 18 months
Feeding time: Once a day
Diet: Omnivorous, will feed on phytoplankton, worms, yabbies, and other dry foods.
Water temperature: 59 - 79 °F (15 - 26°C)
Water pH range: 6.5 - 7.5
Channel catfish
Another excellent addition to your aquatic animals for your aquaponics setup is the channel catfish (Ictalurus punctatus). The species is an omnivore that can be fed live food such as insect larvae or worms and high protein pellets. The meat of channel catfish is delicate and delicious. The water determines a Channel catfish's color it lives in; if the water is clear (as it should be in aquaponics), the catfish is dark, almost black. The catfish might be yellow if the water is turbid.
Growth rate: 1 pound within six months
Feeding time: Once a day
Diet: Omnivorous, will feed on phytoplankton, worms, yabbies, and other dry foods.
Water temperature: 75 - 85 °F (24 - 29°C)
Water pH range: 7.0 - 8.5
Brown bullhead catfish
Eastern North America is home to brown bullhead catfish (Ameriurus nebulosus). They are often referred to as trash fish since they have a sour taste when developed in filthy water. They do, however, work in an aquaponics system because mechanical filtration and recirculation keep the water in the tanks clean. The prominent serrations on the edge of this species' spine make it easy to identify. They are similarly brown and appear dark gray at times, with a cream-colored belly.
Growth rate: 1.1 pounds within two years
Feeding time: Once or twice a day
Diet: Omnivorous, will eat algae, insects, mollusks, crustaceans, crayfish, and other fish.
Water temperature: 65 - 75 °F (18 - 24°C)
Water pH range: 5.0 - 7.0
Which species of catfish is best for aquaponics?
Most growers agree that the channel catfish is an excellent choice for aquaponics. The primary reason here is because this species grows rapidly compared with their counterparts. They reach 3 pounds in a year and thrive in massive aquaponics systems due to their quick adaptability to any environment.
They are omnivorous, too, which means they can eat live food like worms and larvae in addition to high-protein pellets. They produce more dissolved solid waste through feeding than tilapia, resulting in improved nutrient cycling. This species is also disease and parasite-resistant, resulting in increased fish yield.
What are the factors to consider in growing catfish in aquaponics?
Stocking density
This factor answers the question, "How many catfish should I stock per gallon of water?" If there are too many fish, the bacteria will be unable to clean the water, resulting in your catfish dying from an excess of ammonia. And if you have too few, there will not be enough nutrients for your plants to grow well.
One pound of fish every eight gallons of water is the recommended stocking density. This is done to alleviate stress and provide them with more oxygen. The amount of water can be exceeded as the system ages, and the nitrifying bacteria become stronger. Catfish develop more quickly in their early breeding years than they do later in life. It takes roughly two years for most fish to reach full maturity. The catfish requires four to five parts per million of oxygen (parts per million).
Water temperature
Although the ideal water temperature for growth is 75 to 85 degrees Fahrenheit, fish can withstand temperatures ranging from just above freezing to over 100 degrees Fahrenheit. Growth and development are stumped at temperatures below 65 degrees Fahrenheit, and feeding activity essentially ceases at temperatures below 50 degrees Fahrenheit. The maximum water temperature where your preferred catfish can survive is around 95 degrees Fahrenheit, and temperatures exceeding 100 degrees Fahrenheit are withstood for a short time.
pH level
Freshwater catfish seem to thrive in a slightly acidic pH range of 5.0 to 7.0. The goal in a tank setting is to avoid pH changes that are too abrupt or too dramatic. If you have other fish in the tank with the catfish, everything you do to keep them healthy will most likely help the catfish stay healthy as well. Sudden pH shifts most commonly cause fish fatalities in aquariums and fish tanks.
Oxygen
One of the most crucial characteristics for growing fish is dissolved oxygen (DO), which is essential for the beneficial nitrifying bacteria that transform fish waste into nutrients that plants can consume. To sustain optimum health and maximum growth, warm water fish, like catfish, require five mg/L. If DO levels fall below one mg/L, they will come to the surface searching for oxygen-rich surface water.
If your DO level reaches an alarming level, try the following steps:
- The dynamic movement of water returning to the container aerates and adds DO to the water. The falling action of water provides aeration. As a result, make the necessary changes to your system setup.
- Avoid overstocking of fish. It is an excellent practice to add no more than 20 kg of fish per 1000 liters of total water.
- Using air pumps is quite beneficial. For each cubic water volume, a rate of 5–8 liters of air per minute is recommended (meter). Use two air stones and position them in opposite corners of the aquarium.
Feeding
Catfish meals are primarily plant-based, while some fish meals and other animal proteins are included in feeds for fry and tiny fingerlings. Soybean, cottonseed, corn, by-products, and wheat by-products are common constituents in catfish meals.
Fish can be fed once every day with as much feed as they ingest without damaging the water quality. However, depending on the quality of the water and the health of the fish, twice feeding can be done.
Tank size
Catfish are benthic fish, which means they graze on the bottom and are important scavengers. They are also easy to produce and rear. It is recommended that when rearing catfish, you utilize a horizontal tank with than a vertical one because this design allows the fish to spread out at the bottom. The fact that each catfish requires 8 gallons of water indicates that you'll need a vast tank unless you only aim to keep a couple of cats with a modest grow bed.
What are the pros and cons of growing catfish in aquaponics?
Like, tilapia, catfish offers advantages to both novice and experienced aquaponics practitioners:
- Breeding catfish is not taxing.
- Catfish is suitable for human nutrition since it possesses various nutrients and minerals.
- Catfish are non-territorial and do well with other fish.
But there are also some areas of concern when you choose to raise catfish for your aquaponics:
- They would require spacious fish tanks.
- Catfish need high protein foods.
- Because catfish lack scales, they can easily be stressed or damaged if not handled correctly.
How to harvest catfish in aquaponics?
Before harvesting the fish, you should cook some of it to detect any off-taste. Suppose you find the taste unsatisfactory, delay your harvest. Try to determine the cause.
Harvest catfish when it reaches 80 - 200 grams following three to five months of cultivation.
Catfish is adaptable to any aquaponics setup available for you. You may consider growing this fish commercially because of its sweet and mild taste, coupled with its nutritional value. To care for your fish, you may need a huge tank, which means you can have a large grow bed, potentially increasing your plant productivity. Still, you would need to conduct personal research in order to know the proper approach for your catfish aquaponics.
