I agree with the space explanation. Deformity isn't helping either. Also, many fish grow in spurts. Fleshy diet and varied diet help the growth of big cats.
Too bad you don't do pics. We don't get many members from Hawaii. It'd be nice to see what you got, especially outside. Hawaii is very restrictive regarding what freshwater fish you can bring in because they are afraid of a possible damage to their small and vulnerable freshwater eco-system, right? Good to see there still are enthusiasts out there.