i found this one in one website i thought i wanna share it with you... HOPE THIS ONE HELPS!!!
This is the sudden, clean breaking of rays of fins(esp ventral and tail) which appear like being cut. This usually occur when the fish is under tremendous stress, eg jumping out of tank. It is believef by some a natural mechanism for the fish to break away from the predator when caught. similar to tail-dropping mechanism of some lizard.
Possible Cause Diagnosis Treatment
Stress(eg jumping out, sudden large water parameter change) -Cutting edge break of fin rays(often the first few of the ventral fin) -leave it alone if gap of the break is not visible.
-cut the broken rays if gap is visible.
Unfortunately, when this happen, the chance of the fin recovering to its original beuty is slim. Even when the breaking gap is not visible, the broken rays will atrophy and end up slightly smaller and shorter then the others. On the other hand, if the broken fin drop out spontaneously or cut out, the chance of a visible band in regenerated fin is high. In this situation, it is not uncommon that keeper choose to recut the whole fin and wish for the fin to grow back more even. But then, the outcome is again unpredictable.
It is important to provide good water condition during the recovery phase to promote healing and prevent infection. Feed the fish good balance diet, add 0.3% salt & acraflavine and do more frequent water change. Healing take months.