just as an example, i have a 9 month old super veil angel, and he was already over 10 inches from top to bottom at 6 months old. now i think he is pushing a foot in height. he was kept in a 55g tank, and very rarely spread his fins out and seemed cramped. now, in a 150g tank, his fins are spread all the time. a 10g is not only too small for long-term, but cramped conditions can cause fin deformities, even in standard-finned angels.