Edit: did say that it hadn't been done in home tanks but just googled and it is possible but IMO very very unlikey
Breeding
Clown loaches have been bred in aquariums, however it is very rare. Sexing clown loaches externally is hard, but possible by looking at the tail fin. The tail fin tips on the male are slightly bent inwards, making the fin look a little bit like a claw. The tail fin tips on the females aren't shaped like this.
Clown loaches have to be quite old and at least 7 inches / 17 cm before they are sexually mature. In the one good account of clown loaches spawning they spawned under the following conditions:
Temp: 84F
pH: 6.5
Ammonia & Nitrite: 0
Nitrate: < 25
Four large clown loaches (over 25 cm /10 inches) were kept together in a planted aquarium, and a few weeks before spawning they changed their behaviour and started eating live fish as their only accepted food. The females in the group grew very fast on this diet, and had doubled in girth by the time of spawning. The night during which the spawning took place, two clowns were swimming close beneath the surface entwined in each other and "clicking." The next morning, 450 eggs were found spread about the aquarium. Clown loaches eat their own eggs, so it is recommended moving the parents if you wish to succeed in spawning them.
The fry were fed liquid fry food for the first two weeks, after which they accepted crushed flakes. They grew relatively fast, to 2.5 cm/ 1 inch in 6 weeks. After that the growth rate slowed down.
It's suggested that older fish are essential for breeding since this fish might have to be quite old to be sexually mature. Clown loaches live to be about 50 years, so it is quite feasible that they may spawn later in life than many other species.
section taken from here.
