[TheFishGuy]

The amount of fry depends on the maturity of the female, how big she is, and how experienced both parents are. Not to mention if the pair is a forced, or naturally selected pair.

We'd need more info!

 

[TheFishGuy]

Ok, Here's what you should do. After they spawn and the fry have been free swimming for ten days remove the parents and move them to the 20L with their favorite piece of decor. Then after they spawn in the 20L and the fry have been free swimming for ten days move them back to the 30. You can either get another tank to move the fry to or give the fry to whatever is eating them....

Your cons are small, don't expect much....