Great idea! You could use your small tank for fry, and keep the mollies, and any other fish in the big tank! I love that idea!!!!
First, here's something I may get down'ed for - Molly moms DO NOT eat their newborns!!! (Mollys are the only kind of live bearers who won't!) It's everyone else who eats them. If you separate the Preggy moms in a nursery box, you'll see!!! You will have a 100 fry in a night!!!! They will eat them, once they "forget" that that's their own offspring though, so seperate them within 24 hours of being born.
Second, I try to keep 2 females for every 1 male. I don't do mollies though (too sensitive for my tank!) I keep platties. I have all sorts of various kinds of platties (micky mouse, red wag, sunburst, hi-fin etc.) so the fry will be all different! Right now, I have 4 females, (2 ready to explode!) and 2 males. ALL different.
No, DO NOT change the water just after the fish have fry. You don't want to disturb the fry. If they've found a decent hiding spot in the tank, you don't want them coming out and getting eaten. If you're going to let the molly have her fry in the small tank, (in a nursery box I'd hope) then you can hold the fry in the box for a little while, (so you can keep an eye on them, and watch how fast they grow!)
Just in case your fish has fry while you're not paying attention, make sure you have lots of hiding spots in the big tank. Lots of short plants, crevices, and other things to protect the fry from the big fish. Anything that the big ones can't get into.
To get started:
Make sure you have some sort of starter fish (tetras, zebras, guppies - another fabulous breeder!) to get the tank bacteria started. Use some of the big tank's water to get the small tank started, or "borrow the starters for the little tank for a little while. let them stay like that for about a couple weeks, at the least. do a partial change, then you can start throwing a few fish in, like mollies. get you one trio of mollies to start with. then in a couple more weeks, get you another trio. That way they can develop a relationship with each other.
Again, I love your idea! My sister is doing the same exact thing - a 29 gallon community tank, a 10 gallon quarantine tank, & a 10 gallon fry tank (right now with zebra, molly, and some of my platty fry!)
Have fun with it! Mix & Match your live bearers till you find your fav!
Good luck!!!!
;o)
