fast for a fish that's only 14-18 months old. they're Convicts, not Amphs or Oscars. Takes 2-4 months of age to reach 1/2", so growth rate would be like ...1/4" per month, so every 4 months adds another inch, sounds about rightAre you saying his growth is faster than usual or it could be faster?
He's in a 48x18x12 45 gallon with some tiger barbs.