What is this?

This is a fish beside a drain at school. We found 18 fish around our school.
Why are they there?
They are not real so they must be telling us something!
When the water goes down the drain, the water goes to the river where the fish are.
What is a drain?
Something that water goes down. 
It takes the water to a pipe.
The pipe takes the water past the next drain.
It takes the water to the sea or the river.
We have to keep rubbish away from the drains because it will go to river and make the river dirty