They are a vertebrate. They have a brain, spinal cord and neural net
throughout their body... just like any mammal or reptile. The thing is,

a fish can't scream so how can we know it's in pain?

I guess I believe the scientists. They say no nervous system=no pain,
just a reactive system. I believe they feel pressure, the same way a
person can feel a doctor cut into them without pain when they've been
anesthetized first. But I'm open minded to both arguments and would
rather err on the side of caution.

If think I'd rather do the refridgerator thing than whack my little
black goldfish.

Jeanne