Males tend to be more brightly coloured than girls, but the latter is required to make sure peace and stability inside your team of danios. I'd personally say this sort of Betta is a tad more challenging to keep due to the fragile crownlike fin texture. This curious-searching Blue Dolphin https://www.diigo.com/item/note/9tt3x/b27r?k=2b3f4d10222e0e076abad039c47f0ae0