i know youd need an immense tank(like 120 gallons for 2),because they are more intolerant of each other than male bettas guarding bubble nests 4 inches apart from each other. they are also egg scatterrers(as fdsh5 said) and wont take care of there egs.if i were to try to breed them,i would have a large tank(150 or so gallons),with a sand bottom(not that it really matters),with lots of decorations(primarily driftwood),and blackwater(i read it could make them healthier,even if it doesnt it looks cool). i woulod take the water down a couple inches and raise the temp for a month or 2,then raise the water level with cooler water and lower the temp.for best results a tank thats like 300+ gallons would be best