The Redtail Catfish is an extremely fast growing freshwater member of the catfish family. There are two different species of Redtail Catfish that originate from two very distant areas of the world. The South American Redtail Catfish (Phractocephalus hemioliopterus) is native to Ecuadar, Venezuela, Guyana, Colombia, Peru, Bolivia, and Brazil while the Asian Redtail catfish (Hemibagrus wyckioides) is mainly native to Thailand but can also be found in the Malay Peninsula, Cambodia, Borneo, Java, and Sumatra.
The South American Redtail catfish is called cajaro in Spanish, and pirarara in Portuguese, and has also been called guacamayo, bigorilo, pez torre, laitu, parabepre, Banana Catfish, Flat-nosed Catfish, and Antenna Catfish. It is of the order Siluriformes, family Pimelodidae, and genus Phractocephalus. It is the only known existing member of its species under this genus; other related members of the genus, like the Phractocephalus acreornatus from the Solimōes Formation in Acre, Brazil have been discovered, but only through fossil evidence. The genus originated in the Miocene era and is at least 13.5 million years old.
The South American Red Tail Catfish is native to many countries in South America due to the expansiveness of the Amazon River basin. In the Amazon River they exist in Ecuador, Guyana, Colombia, Peru, and Bolivia. They are also located in the Orinoco River basin, which covers much of Venezuela and Eastern Colombia, as well as the Essequibo River basin that flows near the shared border of Brazil and Guyana. They have also been reported in the United States in Florida, Nebraska, Missouri, Tennessee, and Texas, but are nonindigenous to these areas and were most likely pets that had been wrongly released by their previous owners. They have a low probability of becoming an ecological risk in these places that they are not native to besides potentially in the more tropical climate of Florida.
Due to their native location, South American Redtail Catfish are used to a tropical environment. They require a water temperature between 20 and 26°C (68-79°F) and a pH between 6.0 and 7.5. They only exist in freshwater, and thrive best in deep river waters, but have been found to live well in many environments. They can do well in the rapids of a river, and have made their way into forests during flood season, but they are most comfortable staying near the bottom of large rivers, lakes, lagoons, estuaries, or deep pools in streams. Size
South American Redtail Catfish can grow to be very large, especially in the wild. While they can grow to be almost 2 meters (almost 6 feet) in the wild, in captivity their average size is around 1.35 meters (4 ft. 4in.). There is a misconception that the fish will grow to be smaller in a smaller tank but this is not the case. While Redtail Catfish in captivity do grow to be smaller on average, they will still grow to several feet fairly quickly, and can grow at a rate of one inch each week.
The South American Redtail Catfish is known for being one of the most attractive catfish, and has been referred to as the “emperor of the Amazon”. Their long bodies are large and meaty with the flat bellies and wide mouths that are characteristic of catfish. They have especially long “whiskers” or barbels on their upper jaw, as well as two pairs on their lower jaw. Their eyes are wide-set on either side of their head, and they do not have teeth. These catfish are gray colored on the top of their bodies, often with dark spots towards their heads. The lower part of their body is often white or yellow beginning from below their mouth and continuing along their body in a long stripe to the start of their tail fin. In younger fish the stripe is an unbroken strip of white, but as they get older, darker spots begin to break up the stripe. They get their name from the striking and noticeable pinkish red coloring that highlights the tip of all of their fins and the entirety of their tail fin.
While some people theorize that the red coloration on the tail fin of the catfish may be an indication of sex, there is no known external difference to give away the sex of the fish.
Redtail Catfish are bottom dwellers that move through their environment slowly. They are territorial fish and are aggressive to other similar Catfish and to fish that are smaller than them. Redtail Catfish generally eat at nighttime and stay motionless near the bottom of the river or tank during the daytime. They are able to see, and their whiskers are one of their most valuable tools. Their whiskers are very sensitive to touch, and have chemical receptors on them, which they use as a sense of smell. Redtail Catfish will also use chemoreceptors left behind by other fish to find their meal. Catfish will sometimes shed their skin, which shuts down their chemoreceptors. They stop feeding during this period because they have temporarily lost their hunting tools. When they sense a threat they will make a clicking sound as an attempt to ward off dangers.
Breeding in captivity has not been possible due to the large size of the Redtail Catfish, however they have been bred in South American fisheries with hormones. They breed using external fertilization after the eggs have already been laid. The reproduction process has been observed in commercial fisheries, and in this environment incubation takes 30-38 hours at 28°C (82.4°F). The female Catfish will find a safe and hidden place to nestle into rocks and vegetation where she can lay her eggs and be able to defend them from predators. Anywhere from a couple hundred to 20,000 eggs can be laid in one spawning. Younger Redtail Catfish will lay fewer eggs while older and bigger ones will lay more. The male catfish will spray the already laid eggs with his sperm to fertilize them and they will hatch in the next ten days. It is unknown if it is the male or female catfish that guards the eggs while they are hatching. One of them will also guard the newly hatched fish for about a week before they go off on their own. The juveniles became fully developed within 30 days and were an average of 42mm long.
South American Redtail Catfish are omnivores, but prefer meat. These fish are known for eating basically everything that it comes across that fits in its mouth, and in the wild it will eat mostly other fish, but may also eat shrimp, crabs, and fruits and seeds that have fallen into the water when it has made its way into a flooded forest. Because of its diet, the Redtail Catfish does not do well sharing its aquarium with other fish. They can eat anything that is up to half their size and sometimes more. Due to their size, it is a common issue for them to be overfed in an aquarium, which makes them sluggish and sick. The Redtail Catfish is a very slow-moving fish that lives and eats near the rocks in the bottom of its chosen body of water. They have developed chemosensory and tactile abilities that they use to find their prey.
Because of their impressive size and appearance, Redtail Catfish have become a popular fish to keep in aquariums for enthusiasts or advanced aquarists and Amazon themed exhibits. However, their point of interest is also what makes them very difficult to keep as pets. When they are young they are only a few inches long, but they grow very large very quickly and require a tank that holds at least 10,000 L (2,600 US gal) with an industrial filtration system when they are fully grown. Some aquarists say that 1,000-gallon tank is the absolute smallest size that can be used to house these fish.
Their size has also made them a popular fish by anglers to be caught as game. Because they are so enormous, they put up a significant fight and are heavy to lift out of the water. Since they have such a diverse and willing diet, they can be caught with a large variety of baits, but they are often most tempted by live bait. When they are hooked they will make a break for something to escape to like brush or a submerged logs, and will fight for a sustained period of time. However, once they are near the surface they will be easier to spot because of their stand out markings. The International Game Fish Association (IFGA) shows that the current world record weight for this fish is 56 kg. (123 lbs. 7 oz.), and is held by Gilberto Fernandes. He caught this gigantic fish in the Amazon River on April 3, 2010. Redtail Catfish are not dangerous to humans.
Although the Redtail Catfish is a large, meaty fish on the Amazon, locals do not eat them. According to Dr. Herbert R. Axelrod in the book ‘Aquarium Fishes of the World (1988)’, natives to the area will not eat the fish because it has dark flesh. In an attempt to change the color of its flesh to make the fish an edible option, a hybrid version of the fish has been developed to have white flesh by combining the Redtail Catfish with fish like a Tiger Shovelnose, thus creating the Tiger Redtail Catfish.
These fish are popular due to their size and coloring, however they are very difficult to keep in an aquarium. They can cost anywhere from $17 to $500 depending on their development and size. They grow very quickly and require a massive aquarium tank with a powerful filtration system, and a knowledgeable and dedicated caretaker. Their tanks do not need many accessories and they have been known to eat or choke on rocks, however they are capable of spitting things out of their mouths. Breeding is also not possible in captivity because of their large size. Redtail Catfish do well with other tank mates of their size and will eat anything in their tank that is smaller than them. They can live up to 20 years if they are cared for properly, so they require decades of commitment and care.
Redtail Catfish are not considered an endangered species and are not at risk. They are a hardier fish that is not easily susceptible to diseases, can live in a wide variety of environments, and as omnivores they can be sustained by many different kinds of foods. While they are sometimes consumed for food, native populations do not eat them so they are not in danger of being over fished.
Although the Asian Redtail Catfish has a similar common name to the South American Redtail Catfish, they are technically of a different species and genus. Their binomial name is Hemibagrus wyckioides, and they are of the order Siluriformes, the family of Bagridae, and genus Hemibagrus. They are also called Common Baung, Pla Kayeng Thong, and Trey Khya in local languages. These fish are native to the Mekong River system, which is spread throughout China, Laos, Vietnam, Cambodia, and Thailand. They also live in the Chao Phraya drainage area in Thailand. There are some records of the fish in Southern China, the Malay Peninsula, and the island of Java, Indonesia.
The Asian Redtail Catfish has been identified as one of the most aggressive species of catfish because of its fierce hunting skills and tendency to eat anything it can get its mouth on. The South American Redtail Catfish and Asian Redtail Catfish have very similar characteristics and lifestyles. The only differences are that they are different species from a different genus, they live in different parts of the world, and Asian Redtail Catfish are eaten by locals and are a larger part of the local economy than their South American counterparts.