Holes in the fins are the beginning of fin rot - but it usually starts with high levels of ammonia.
How big's his tank, and how often do you change the water?
There's a good bit of information in the sticky thread on diseases at the top of this forum section re treating fin rot with aquarium salt. It'll probably be quite effective, at this stage too, as it's only the beginning of rot.
It's essential that you make sure he has clean water -- in fact, he very well may heal with just clean, warm water alone, so that's why I'm asking tank size/change schedule.
Last edited by Aus; 07-22-2012 at 06:47 AM.