Brett....I have NO idea.....LOL ! I'd say at least 20-30 fry give or take a few. I started out with one male and two females. Didn't take long at all to need a 20L for the lot of them. Great fish !!
The stappersi I have I am raising a batch of roughly 20-30 fry in a 5 gallon at present. I removed them from the tank with the adults because the last batch disappeared when I left them in. These are doing great and growing nicely.
Definitely check out ebay for shells. Do a search for either escargot or whale eye shells. That's how I found that batch that I purchased, a definite DEAL ! Not a single broken shell in the bunch and all different sizes...only a few are really too small to be used by the adults, but the fry should take a liking to those.