It is possible to breed Loaches in aquariums, but it is very rare. To begin with, sexing Loaches based on external features is hard. The tail fin tip on a male Loach will however be slightly bent inwards. If the tail fin looks somewhat like a claw, it is probably a male Loach. Female Loaches will not have bent tail fins. You also have to wait until the Loaches are old enough to breed. They usually grow to at least 7 inches (17 centimetres) before they turn sexually mature. Loaches can become 50 years old, so it is not rash to assume that they need to be much older than many other fish species before they can successfully reproduce. You will therefore probably increase the chances of getting Loaches to spawn if your try with rather old individuals.
There is a reported instance of Loaches breeding in an aquarium. In this case, four Loaches measuring over 10 inches (25 centimetres) were kept together in a planted aquarium. The water temperature was 84 degrees Fahrenheit. The ammonia and nitrite levels were kept at zero, and the nitrate level below 25. The pH was 6.5.
A few weeks before the spawning occurred, the Loaches changed their normal behaviour and accepted no other food than live fish. This new diet made the females grow very rapidly, and before the spawning commenced their girth size was twice as big as prior to the change of feeding habit.
During the night when the spawning occurred, two Loaches were seen swimming close under the surface entwined in each other. They were producing clicking sounds. The morning after, 450 eggs had been deposited in the aquarium. If your Loaches spawn, you should remove the fish from the aquarium afterwards since they will otherwise eat the eggs.
The Loach fry were given liquid fry food during their first two weeks. As they grow larger, they began to eat pulverised flake food. The fry grew comparatively fast and had reached a length of 1 inch (2.5 centimetres) after 6 weeks. After reaching this length, their growth rate slowed down.
