Lightfish were small, glowing fish found in the deepest underwater caves around Ga-Metru1 and Ga-Koro.2 Ga-Matoran on Mata Nui used lightfish to provide illumination for their dwellings.2
Notes
Lightfish glowed in the dark and hovered in the water, waiting for prey to swim by. They never stopped glowing as long as they were alive.3
The blue, bioluminescent sea creatures seen in the Mata Nui Online Game and Last Moment Save were lightfish.4