'Fish' signs on trucks/trailers

Factual Questions
1

I’ve noticed that on some delivery trucks, there is a sign on the truck or trailer that reads ‘FISH’. Why is that? It’s not like a truck full of potatoes has a ‘potatoes’ placard on the outside.

Hazardous materials such as explosives or corrosive items I can understand, but fish?

2

Fish meal or fish scrap is considered a hazardous material. That’s probably what it is.

Haj

3

Because it is the law in at least one state:

Ohio Revised Code (pdf, pg. 2)

4

Previous thread

5

thanks