Sea World/ABC News

A killer whale at SeaWorld in San Diego is recovering from a nasty gash to its jaw that is the subject of a dispute between the park and the animal rights group PETA.

SeaWorld says the 11-year-old killer whale named Nakai was injured during a show last month when he somehow came in contact with a portion of the pool. The gaping hole is so big that Nakai's jawbone was left exposed.

PETA says an anonymous whistle-blower told them that Nakai was attacked by other captive, angry orcas at the park.

"You can't keep three young males together in what is, for them a fishpond or a fishbowl," PETA president and co-founder Ingrid Newkirk told ABC News. "They will have nowhere to go unless they can swim through concrete when they feel aggressive towards each other."

The animal rights group has filed a complaint with the U.S. Department of Agriculture, saying it wants SeaWorld disciplined for not keeping the whales separated as required under the Animal Welfare Act. The law requires incompatible marine mammals to be kept in separate enclosures, PETA said

SeaWorld says veterinarians determined the injury was not a result of an animal bite and provided video to ABC News showing Nakai on the mend. Trainers and veterinarians say they are closely monitoring his recovery and treating him with antibiotics.

"He's [Nakai] doing very well and interacting with all the other whales and trainers," said Kristi Burtis, supervisor of animal training at SeaWorld.

Nakai is a killer whale with a violent family tree. Nakai's father, Tilikum, was the orca that killed a trainer at SeaWorld in Orlando two years ago.

"It's hard to tell if they're just playing rough or if these are just aggressive interactions between individuals," said Robert Pitman of the National Marine Fisheries Service in San Diego.