This site has several amazing photographs of koi by Jesse Rockwell as she discover a "secret subterranean aquarium.
In most post-apocalyptic films when the camera pans down the abandoned streets of New York or Tokyo, long after people have disappeared and the buildings have fallen into disrepair, we see nature again thriving. Trees and plants take hold in the sidewalks and wild animals like deer, bears, and lions stalk the ruins left behind by humans. But after descending the staircase at a vacant shopping mall in Bangkok, professional cook and photographer Jesse Rockwell discovered a wholly different take on beasts inheriting the Earth: fish. Specifically exotic koi and catfish, teeming by the thousands in a secret subterranean aquarium. Rockwell shares via his blog:
An Abandoned Bangkok Shopping Mall Hides a Fishy Secret | Colossal (thisiscolossal.com)