That's right, paint thinner.
Or maybe someone was doing some DIY nearby.
I didn't exactly have high hopes for this place, but I was expecting it to be decent at least. In the end, I'm not sure what the fish was. It was thick and meaty, but tough as an old boot, and yes, it had a distinct aftertaste of paint thinner, which is actually a smell I'm quite keen on. Not to eat though.