Here's why:
* Sand fish are reptiles. Reptiles are adapted to living on land, and their respiratory systems are designed to breathe air, not water.
* They are desert creatures. Sand fish are found in the deserts of Africa and Asia, where water is scarce.
* They burrow in the sand. Sand fish use their bodies and scales to move through the sand, seeking out cooler temperatures and escaping predators.
While they can hold their breath for a surprisingly long time (up to 10 minutes), they don't spend any time underwater.