lets clear this up for one and all
some brilliant advice as ever given above....
tank size varies breeding schedules greatly depending on set up, fish kept, budget etc.....lighting, filtration, temp, substrate, food.. the list goes on..
if the fish want to breed they will... though we try to trigger them with little variations which can be found here....
if you are worried about fry loss then just do a water change every couple of days, and be prepared to remove some to a fry saver to make it easier.
As mentioned it is harder to maintain water stability in a smaller tank than a bigger tank.
We all prefer bigger tanks, though I have experimented recently with 2 x 5 gallon tanks which have had a water change every third day.
And need I just say that both have a breeding pair of BN in them and both have spawned within a few days of adding a male to the female already in them.
I have now sold one of them to a fellow fish keeper for breeding shrimps, but I still have kept 1 x 5gallon aquarium and the male and female are in there now watching over a spawn of around 50 eggs.
Start small and when budget, experience and time allow then invest in a set up a little bigger.
This is a briiliant web site full of fellow fish keepers willing to help.
Enjoy your new hobby and along the way your experience will help to best utilise the equipment you have at the time
Though just monitor the set up, and ensure it does not get over stocked, and never forget the regular water changes.
kind regards and good luck..