The betta thread on the old forum was really cool, so I thought I'd revive it!
The more pics you have, the better!
Enigma: Bought as a female, had a great debate whether he was male or female, finally decided he was female, added a couple of other "females", and found some rather large bubble nests the next day. Now confirmed he's male
This is actually an old pic, but he rarely flares these days, so I don't have a more recent flaring pic!
And a more recent pic. The flash makes him look green, but he still looks blue like in the first pic:
Pixel: Bought as female, but had a pretty good hunch he was male (and he is). He was so tiny when I got him! He's grown quite a lot now.
Baby picture of him:
More recent vid of him flaring:
Mango: One of the "females" I bought to put with Enigma, but also a male. He recently injured himself on something (my best guess is the lid of the tank), so now he's got a wonky jaw and stubby ventral fin, but it doesn't seem to affect him.
Rosemary: The other female I got. She's actually female

She's got a "lucky fin", like Nemo ^_^ Her left pectoral fin is about half the normal size. It doesn't slow her down a bit, and I didn't even notice it until I'd had her for a couple of weeks!
Shows her lovely colours:
And my most recent addition, Marmaduke. My very first veiltail betta. He's a big boy, so I suspect that he's already a couple years old, but I just fell in love with his colours. He's sort of a "dirty" orange dalmatian.
Shows his spots: