Just wonder what the usual protocol when breeding fighters? We have introduced the female to the males tank in a cup, as soon as she entered he started flaring and swimming round frantically. He has made a start to a bubble nest, what next?

If you want to spawn Bettas, you need at least a 10G tank. The classic way is to put lots of floating plants in the tank, run the temp up to 85, add the male, wait a few days and then add the female. The female needs to be rounded and full of eggs. Males usually go crazy once they see the female. Once spawning is complete, take the female out. As eggs fall out of the nest the make puts them back in. Once the fry become free swiming you can take the male out. The fry need very fine food, like protozoa or algae. Many will feed directly off your plants.

what filtration is best, sponge or corner?

FIrst off,you need to condition the pair to each other.Feed them live and frozen foods for two weeks,having them sit near each other.Place an index card or piece of paper betwen the tanks.Let them see each other for a few minutes each day.Feed them three times a day.This will help the female build up alot of eggs and the male to gather his strength.Breeding is very hard on bettas and i do not suggest doing so unless you have a goal.Such as,showing.If they are pet store fish,then the genetics are unknown and could have very undesireable traits.Before conditioning you need to gather live food cultures.Vinegar eels for very small fry,microworms,for larger,though i hate using them as they sink and could lead to ventralless fish.Grindal worms,and baby brine shrimp cysts.I do not recomend egg yolk as its only food for the organisms on the live plants,and the bettas will not eat it.It will foul the water really fast if not careful.Get your cultures going so the fry will be able to eat,and condition the pair.Once ready(BTW,start collecting jars and lots of them...)Set a ten gallon tank up,bare bottomed.You need a half a styro cup or an Indian Almond leaf(The best thing,IMO)for the male to nest under.Have this in one corner.In an opposite corner,lay some java moss,and other floating plants,as well as a terra cotta pot with a hole large enough for the female.This is so she can hide.You want a sponge filter,and a flow valve,to set the filter to one bubble every few seconds.Place the male in,and let him get used to this.The next day add the female.I dont put her in anything,just throw her in.He will flare and dance,and beat the living crap out of her.This is normal,do freak out.As long as she starts swimming with her head down and gets verticle bars(NOT HORIZONTAL,THESE ARE STRESS) and hes not chasing and trying to pummel her into the tank walls,they should do fine.Just watch them.A female can very easily kill a docile male and they can also become swimming buddies and not spawn.

I heat my spawn tanks to 90.Slowly mind you.But i blacken it with IAL extract too(depending on the fish).
Heres a few pics of my setups:

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I know it wasn't for me but very nice info majerah1.

You are most welcome,snail.Its one of my goals to make sure anyone breeding these fish knows what they are getting themselves into.Its a very difficult path to take,becaue all the different fin types and the defects they can have.

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