Covenant koi
From Halopedia, the Halo wiki
Covenant Koi (tentative name) are a species of fish similar to Earth Koi and Goldfish.
The Covenant apparently make similar use of them as Humans do of their counterparts, namely that of a decorative pond fish. A school of fish was kept in a garden in High Charity . The presence of Unggoy in and near the pond may suggest that Unggoy consider them food.
They can be found on the level Gravemind, in the central pond of the Valley of Tears B section within High Charity.
