KPIX Anchor Veronica De La Cruz says that she was attacked and bitten by a small tropical fish. 

De La Cruz says that he was on vacation and was snorkeling in Koh Kradan, Thailand on Wednesday when the fish attacked. 

"I was surprised," De La Cruz said, "We were snorkeling and I was floating above a bunch of tropical fish. I noticed one in particular--a black one with different rainbow colors--8 to 12 inches long, seemed particularly agitated. She kept swimming past us back and forth until finally she backed up as far as she could and charged for me."

"She sunk her teeth into my leg. I jumped out of the water and started screaming," De La Cruz said.

"My first thought was -- is this thing poisonous?! And holy heck, the fish actually drew blood?"
After checking in with the dive shop, divers assured her the fish was not likely to be poisonous, but workers helped her disinfect the leg wound with alcohol.

But, as for why it attacked?

Fish bites are fairly rare, but a quick scan of various travel blogs shows they do happen every so often, usually with the same minimal damage to the human.
Locals think this particular fish bite was from a female, and the human swimming too close to her eggs caused her to go defensive.

Sounds like a May book sweeps story. 

"Can your goldfish kill you?.... tonight at 11"

H/T SF Chronicle