Breeding aquarium fish can be a joy and a challenge for aqua hobbyists. Some species like guppies and swordtails breed easily and frequently in the home aquarium, while other species are rarely known to breed in captivity. Some species of freshwater fish, like the red-tailed shark, are difficult to breed in captivity but it can be done with the right equipment and preparation. Before you attempt to breed your red-tailed sharks, make sure you have the proper knowledge and equipment to do so.
Create a breeding tank for your sharks. The breeding tank should be large enough to accommodate several sharks happily and to provide space for hiding places should they become aggressive. Use a tank no smaller than 20 gallons for three sharks and ideally no smaller than 40 gallons for five or more sharks.
Keep the sharks in your tank at a high ratio of females to males. Red-tailed sharks are very difficult to sex so it may take some time to differentiate between the two sexes. Female red-tailed sharks may be larger than males and may have a wider and fuller stomach whereas the male shark will be slender. The female may also have a slightly less-pointed dorsal fin.
Decorate your breeding tank with rocks and driftwood. Provide your sharks with places to hide such as hollow logs or rock caves. These places may also be used as egg-laying sites if you are able to get your sharks to spawn.
Plant your tank abundantly with live plants. Cultivate a variety of plants in bunches throughout the aquarium.
Maintain a water temperature between 79 and 82 degrees Fahrenheit with the help of a submersible aquarium heater. Monitor the temperature with a sunken thermometer.
Monitor the pH of your shark's tank and make adjustments when necessary. The ideal pH level for red-tailed sharks is between 6.5 and 7.6. Adding peat moss to the aquarium can help to regulate pH and to acidify soft water.
Watch your sharks for mating behavior. Little is known about the breeding and spawning process of red-tailed sharks, so keep a close eye on their interactions. A spawning tube sometimes appears on the male several weeks before spawning occurs and the male fertilizes the eggs as they are released from the female.
Keep the breeding pair of sharks in the tank after spawning has occurred and remove all other sharks. Watch the sharks closely to determine whether they will care for the eggs or if they will eat them. One or both of your sharks may guard the eggs, fanning the water around them. If your sharks seem to be ignoring the eggs or if they begin eating them, remove the sharks from the tank.
Wait two days or so for the fry to hatch. For the first two days they may not move far but after a few days they will become free-swimming. After the fry have consumed the remainder of their yolk sacs, you will need to feed them.
Feed the fry a combination of different foods to determine what they respond to best. To start, hatch live brine shrimp eggs and offer them to the red-tailed shark fry. Over time, you may be able to wean the sharks off live food and onto commercial fry foods or finely crushed flake or pellet foods.