It may be just something that "happened". You should watch for deteriorating fins, or eroding fins. Be sure that the fish is offered amble food suited to its species. Keep a close eye out for developing problems, or healing.
Originally Posted by new-guy http:///forum/post/2685732
sorry i dont have a digital camera. its a slit in the middle of the top fin almost a tear in it it dosnt look like a fish has been nipping at it.
My sailfin gets slits in his fins every once in a while too. It's not a great cause for concern, the fin will repair itself over time. Not exactly sure what causes this to happen but I think it's just from rubbing on a rock or the fish over expanding it's fin maybe.