Polypterus senegalus, the longnose gar (Lepisosteus osseus) and the bowfin (Amia calva) had gulonolactone oxidase activity in the kidney and thus can synthesize ascorbic acid(VITAMIN C) (Journal of Fish BiologyVolume 57 Issue 3 Page 733 - September 2000)
So you don't need to add Vitamin C
So you don't need to add Vitamin C