From Halopedia, the Halo wiki
A fish is any member of a paraphyletic group of organisms that consist of all gill-bearing aquatic craniate animals that lack limbs with digits. Different types of fish exist on human-occupied worlds, Sanghelios, and Forerunner installations, and there were even fish on High Charity before it fell. An ice shark is a type of shark found in the waters of Draco III.
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