Gar

Gar was an Onu-Matoran and Defilak's best friend. He volunteered to helm Defilak's Underwater Submarine but was captured by Pridak along with the rest of the crew. After Pridak left with Defilak, Gar offered to sacrifice himself to allow Idris to get to Mahri Nui and warn the Matoran there, even though he barely knew her. This was not needed, as both got to the airweed fields which were occupied by Carapar's Keras army. The recently escaped Defilak rescued both and helped the two return to the safety of Mahri Nui. The Toa Mahri then led Gar and the other Mahri Nui Matoran to Voya Nui. Axonn took them to the Nui Caves to survive the descent. For a while he lived on the Southern Continent before evacuating the Matoran Universe and taking up residence on Spherus Magna.

Trivia
A 'Gar' is a real-world river fish.