Jewel-like fish circle the underwater reef while hundreds of sharks have hunted them in packs.?

The sentence is grammatically incorrect and a bit confusing. Here's a revised version that makes more sense:

Jewel-like fish darted around the underwater reef, their bright colors a stark contrast to the lurking shadows of hundreds of sharks.

Here's why the original sentence was problematic:

* Tense inconsistency: The sentence uses both present tense ("circle") and past tense ("have hunted"). This creates a confusing timeline.

* Awkward phrasing: "Hundreds of sharks have hunted them in packs" sounds a bit clunky and doesn't quite convey the dynamic action of the scene.

* Ambiguity: The original sentence implies that the sharks are currently hunting the fish, which isn't clear from the wording.

The revised sentence clarifies the tense, adds more vivid imagery, and conveys a sense of danger and tension in the scene.