What is a fish with big mouth and can go 16000 feet depth?

The fish you're describing is most likely the anglerfish. While not all anglerfish can reach depths of 16,000 feet, some species, like the deep-sea anglerfish, live in the abyssal zone of the ocean, which can be as deep as 13,000 feet.

Here's why anglerfish fit your description:

* Big Mouth: Anglerfish have enormous mouths relative to their body size, with sharp, fang-like teeth. This allows them to catch prey much larger than themselves.

* Deep-Sea Habitat: Deep-sea anglerfish are well-adapted to the extreme pressure and lack of light in the deep ocean. They often have bioluminescent lures to attract prey in the darkness.

Let me know if you'd like to learn more about anglerfish!