Hiya

6 tanks is no where near enough. Bettas can produce 500 fry. And if 250 of them were males, you would need 250 containers. And as i said before just because you have male and female bettas, it doesnt mean you need to breed them.
anyhoo.....
Let them settle for 2 weeks then condition the pair for 2 weeks on live foods as well as dried pellets/flake.
Set up the spawning tank. It should be 5-10G (empty-no other fish allowed!) (no bigger or smaller. Smaller and you will wreck the nest when catching the female/bigger, the fry will get too far and the daddy betta wont get them to put back into the nest, as he has to tend to the others)
A small sponge filter powered by an airpump is needed. Do not turn this on till the fry are free-swimming. Some plants live/silk, they are good for the female when she wants to hide. IALs are needed to induce spawning. A polystrene plank is great for the male to build a nest under and a heater (set it to 30C)
After conditioning the pair. Put the male in the spawning tank and the female in a chimney glass. (or a 2l pop bottle with the top and bottom cut off) Leave her in here for 2 days. In this time the male will build his nest and the female should become eggy.
After these two days release the female but keep a close eye on them. it might take from 2 hours- 2 weeks for them to spawn. They will have an aggressive courtship. Fins will be torn, but if you see its getting very dangerous and she looks really sad then remove her.
After the courtship the should start wrapping. She will release a few eggs each time. He will collect them and place them in the nest.
When he starts chasing after her, this means you need to remove her. Pop her in her own tank and feed her well. (dose with meds if needed)
Do not feed the male until he is removed. The eggs will tank 36-48 hours to hatch. In this time he will be tending to the nest, blowing fungus off and carrying back fallen eggs. He might also pop some bubbles to make new ones. Dont disturb him, as he might eat them if he feels threatened.
Once they have hatched, they will only swim vertically for approx 3 days. The male will carry on taking them back to the nest if they fall. In these 3 days they will still have there yolk sak so there is no need to feed them.
At 3 days old, they should start swimming horizotaly. Turn the filter on now. Remove the male. This is when you can start feeding them. Live foods are best. Things like worm cultures, Baby brine shrimp, Infusoria etc.
What i use atm is Banana+Walter+Microworms Cultures. Infusoria off Live plants and Apple Snails waste. When they are older i will feed them grated Bloodworm and pellets/flakes.
Feed them 4 small quantities, or 2 large quantities.
At 1 week do your first water change. Then at week 2 do another waterchange. When you are at Week 2.5 try doing waterchanges every 2 days.
At about 3 months you will be able to tell the males apart from the females. Remove them into there own containers. And do daily waterchanges on these. They should be warm too.
They are ready to be passed on at 5 months.
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