one of my fish are killing the rest?

Question
I have had an aquarium now for about 6 monthes, and about a month ago of my fish got in a fight and died, and now a second fish got into a similiar fight and has a cut and i dont know which fish would be doing this, and 2 can i help the fish at all?

1 bala shark
1 iridescent shark
4 neon tetras
1 assorted swordtail
1 pleco
1 dalmation Molly (i think)
2 smaller platty's ( i think)

Answer
It sounds like the culprit here may be the Iradescent Shark they are classified as aggressive fish. The only thin gyou can do to help the other fish is to seperate them from the shark. That seems to be the only fish in that group that I could see causing a problem. Good luck!