smurfy, tis is wise and righteous thing you do researching now, getting prepared. 20 gals might be too big for spawning. You want your pair to be able to see each other and not waste all their stamina chasing around. Also, you'll need to keep the tank fairly draft-free--all the tank--so the bubblenest doesn't dissipate in a sudden breeze (like opening the lid). Once spawning starts (the embrace), your male probably won't eat again until after you remove him from the spawning tank so you don't want him wasting energy swimming around a 20 gal. chasing the female or patrolling his territory. I spawn in 5 gal. tanks because I limit how many eggs the female drops. Other folks swear by a 10 gal. tank. In Thailand, they do spawns in mixing bowl size pots--just stick the fish in, put a lid on it so it's fairly dark, and come back a few days later to remove the adult fish. I would avoid anything smaller than a 5 gal. or you'll disturb the bubblenest and/or newborn babies when you try netting out the parent(s)--the parents usually will not cooperate with the plan and trying to net them becomes a big ordeal. Use your 20 gal. as a baby grow out tank. I leave the newborns in the tank they were born in for hte first two weeks, just feeding them and slowly adding clean water. After 2 weeks, that tank is pretty skanky but the babies are big enough to easily see so I use a medicine dropper to suck out the babies and transfer them to a fully-cycled 20 gal. tank where htey can stretch out and grow. They'll need the space.
