in my science room, with the 5 gal that my next batch of fry will go to, there is one of those junior/mini heaters, meant for a 5 gal. the temp seems perfect in there. it doesn't fluctuate like crazy, either.

  in the 5 gal to be, i'm going to keep the male. it could be like his bachelor pad, until the kiddies move in.

  this is sort of my seating chart that i've worked out (for the fry):

  batch #1: stays in net breeder in 10 gal that the mother lives in until 1 week old, then moved to the school's empty 5 gal.

  batch #2: kept in net breeder in 10 gal with
mother until next batch(age 1 month).

 batch #3: batch 2 moved to 5 gal with dad, #3 put into net breeder in 10 gal until NEXT batch.

 batch #4: batch 2 females moved to 10 gal tank with mother, males stay with dad. #3 move in with
dad as well. #4 in net breeder like previous batches, until #5.

#5: batch 2 stays where they are, until sold to LFS. #3 females move with mom, males stay with dad. #4 moves in with dad and other males. #5 moves into net breeder in the female 10 gal.

   *number 6 should be last batch from insemination*

 #6: #2 should be out of house and in with new owners. #3 stays where they are until sold to LFS. #4 separated by gender. #5 moves in with dad. #6 goes into net breeder.

I agree with Scott however.  Even though he might not attack your mollies, he'll definitely munch up your fry with no hesitation.  If you want to make your betta happy, you may consider putting his tank next to the molly tank.  Bettas -love- to watch other fish, especially other bettas.  It keeps them from being lonely and bored.

The setup you're describing is ideal for a betta.  They can be kept happy in even less than a gallon with strenuous water changes, but you don't want that.  Just remember that you don't need to save aside water each time you change a betta tank.  They're very tolerant of dodgy water conditions.  After all, wild bettas live in what equates to big mud puddles, flopping along the ground from puddle to puddle when food is scarce!

They need at least a gallon, but is best to have at least 2 gallons if you want to avoid ALOT of water changes.

The filter isn't absolutely necessary, but it is nice to have. Bettas don't create a whole lot of ammonia, and are capable of breathing air from the surface. With enough water changes it is fine to go without the filter.

My only filtered betta tank is my 10 gallon female tank. (five females in the tank)

Never keep 2-3 females in a tank together. You need at least 4, or just one.

Never keep any more than ONE male together, or they will fight to the death. (there are exceptions to this, but you should NEVER put two males together)

Temperature is the tough one. It all depends on what your betta is used to. I have one that has lived for four years at 68-72 degrees, so I'm afraid to give him a heater because of the shock that could cause.

As long as you stay above 70, your betta should be ok, but above 75 is best. The most important thing is that the temperature stays stable.

Bettas are some of the easiest fish to keep, because they don't require much.