double banded soapfish

Diploprion bifasciatum

This fish has little factories in its skin (glands) that will produce a skin toxin when being hunted/eaten. The molecules of the toxin are arranged in such a way that it is attracted to fats and dissolves into them (just like soap), and it is produced to stop another fish from eating it.

What it also means is that if you put this fish in a washing machine, it would help clean your clothes.