I usually use aquariums for breeding purposes, especially for deathfish, robotfish, and vampirefish. The clownfish seem to be more prolific breeders, though. No more than 6 fish can be in the tank at any time, so you must leave room for the babies. Often I'll have two pairs of breeders, leaving room for 2 offspring. The omniplant is a faster way of reproducing fish, however.