“Researchers have long thought fish were heartless and cold, incapable of the relationships mammals cultivate, but new research among fish in coral reefs suggests fish can work in long-term paired relationships.
By Lucy Schouten, Staff September 29, 2015

“A diver snorkels in the Great Barrier Reef off Australia’s Queensland state. Rabbitfishes from a coral reef have just been found to exhibit reciprocal cooperation, meaning they are the first fish known to take care of each other.
“Fish living in the vast network of coral reefs near Australia are already known to moviegoers for their devotion, thanks to the loving clownfish father-and-son pair in Pixar’s “Finding Nemo.”  From: exposingthebiggame.wordpress.com

GR:  The Bluegill in my ponds defend their nests against predators.  It seems that there are usually two defenders, but I haven’t watched enough to be sure.