Gary is a large Nassau Grouper who lives on the reef off the north side of Little Cayman Island. Far more intelligent and curious than most people would believe, Nassau Groupers can not only understand human behavior, they can also interact with people and try to communicate. Gary has learned that scuba divers often spear Lionfish, an invasive species that are a serious threat to the native fish populations and the health of the reef.
Gary follows scuba divers when they conduct an organized cull of the Lionfish. Researchers and environmentalists have been trying to introduce the notion of Lionfish as prey so they have been feeding the Nassau Groupers under carefully controlled conditions. Gary is one of the fish that have learned not only that humans can be a source of food, but he has also learned how to help locate the Lionfish for the divers. Gary will lead them right to a ledge or crevice that shelters a Lionfish and he will look back and forth at the fish and at the divers until they come and spear them for him. In the process, he raises his fins with excitement while he waits for the diver to come over and find the invader. This is a surprisingly cunning form of cooperation that makes the Lionfish cull more successful. Gary most definitely understands that what he is doing is being understood by the divers.
Gary is also able to recognize Craig as one of the divers who occasionally spearfishes. Craig was leading a group of recreational divers on this occasion and he had no spear, but Gary zeroed in on Craig and greeted him. When Craig sees Gary coming, he playfully turns upside down and performs an inverted spin while Gary comes right up to his face as if he is happy to see Craig. The two look right into each other's eyes before they continue to swim together happily over the reef.
We seldom give animals credit for being intelligent, but this is a clear demonstration of how even a fish is capable of recognizing certain people and forming a bond with them, even if the relationship is based partly on food.
Nassau Groupers are often curious about divers, but Gary has captured the hears of many here on Little Cayman Island. In some ways he is more like a dog than a fish.