Thank you for the advice and compliment. I did originally have them in separate aquariums. The male was living in a cherry shrimp tank when he was about a month old because of his deformities. I haven't seen him eat any cherry shrimp in fact the population of the cherry shrimp increased.(Even when little baby shrimps are next to him he doesn't eat them).
The female I took her out of a sorority since she was not eating enough. She would never swim up to eat during feeding time, only waiting for the leftovers on the gravel if there was any.
So eventually I move the male to the current aquarium with originally two guppies and move the female to the cherry shrimp tank.
Guppies gave birth and I notice he does not eat the babies guppies. I put a mirror in front of him he doesn't flare. He has always been the same since he was a fry. A chill funny looking betta that swims upside down or sideways. I would suspect swim blabber issue but he can swim up and down with ease.
I move the female in the current aquarium and I have not observe any changes in behavior and its probably been 8 months.
But both act the same since birth and they are about 2 years old. I have spawn betta since 1999. I would never fight them or subject to cruelty.
I can separate them but from my understanding most wild bettas (https://en.wikipedia.org/wiki/Peaceful_betta
) are not as aggressive as the splenden betta due to selective spawning for betta aggressiveness and eventually they are the current colorful splenden betta we buy in the fish market.
I think the male betta may have the not aggressive gene or he just mentally challenge.
But If I do see sight of aggression or stress then I will separate them. At night lay next to each other near the intake filter. None of there scales and fins are damage in the past 8 months.
I hope that ease your worries.