All Gillmen believe themselves to be the greatest singers in the world, while others find their singing dreadful. While not appearing in the game, they also have a military organization which the most notable Gillman Skylander, Gill Grunt, used to be part of.
The Gillmen were taken captive by the Trolls, who have also taken over their home, Oilspill Island. One Gillman, Gurglefin, managed to escape and sought out the Skylanders for help in hopes of them freeing his home from the Trolls. The Skylanders agreed to help, and went to Oilpsill Island with Gurglefin, freeing the captive Gillmen, ridding the island of the Trolls, and destroying their oil-spewing machinery that were polluting the waters.