Recently i broke high-fin of one my my paroon's during shifting from one tank to another ,it's not detached completely but maybe in 2-3 days .He is around 20 inch . Will fin grow back ??
Also my arowana head is tilt or forced to stay on 1 side always which looks weird. Anyone Knows about this ?
Not sure on the fin re-growth, if its cut off at the base i'd say no.
For your other question i'd guess some sort of muscular-skeletal deformity caused by/at birth, or by malnutrition, living conditions, injury or disease.