During morning hours, it may be seen basking in the sunlight, almost completely black in color to capture heat energy from the sunlight.
en.wikipedia.org That is not enough to qualify as the longest fish, however, as some of the cartilaginous fish such as the basking shark and whale shark are even longer.
en.wikipedia.org They include the goblin shark, basking shark, megamouth shark, the thresher sharks, shortfin and longfin mako sharks, and great white shark.
en.wikipedia.org Some of the largest epipelagic fishes, such as the basking shark and whale shark are filter feeders, and so are some of the smallest, such as adult sprats and anchovies.
en.wikipedia.org In the morning, while they are still torpid, they move from the rock-crevices to basking sites exposed to the sun.
en.wikipedia.org