Well that really is the main thing. Like you said, as long as he is happy & healthy, that is all that matters.
I think his fry would be beautiful! He has such a lovely combination of colours.
Maybe it does.. could it be that his little body is using its energy to heal, rather than grow? Experts say that the common cold will delay a child's growth for the duration of the cold. This is true for humans, could it be true for Bettas?