system
Given the following post, respond as if you're commenting on Reddit:
human
Chemically speaking, what is "Fishiness?"

A lot of fish and other seafood definitely share this trait, sometimes with smell more than flavor. What causes a fish to be "fishy?"
gpt
In order to keep their hydric balance, marine creatures have to have something inside their cells to be isotonic. What most of them have is trimethylamine oxide, a somewhat volatile compound when broken down to trimethylamine. The problem is, trimethylamine happens to smell... bad.