what are some cool water pets? like cool fish?

I would get a five gallon aquarium. You could get a Betta, Ghost Shrimp, or African Dwarf Frogs in that!

zebra danio are tropical and cold water fish. They are very hardy, stripy fish
easy to look after

can have around six of them

Bettas
Shrimp
Snails

I like Koi, but you will still need an aquarium, etc. for them.
They could live in an outdoor pond. They live quite a long time and have lots of interesting colors. Oriental countries have treasured them for centuries.And some of them are very expensive. But you can get them for lots less and they grow pretty large. They also are said to have individual personalities.

Turtles make good fishbowl pets. Just be sure they have a place to climb out of the water occasionally. They need a clean bowl every day and eat a variety of foods. Mine liked uncooked oatmeal. One got away from us in the house and crawled out from under the sofa a month later.

Sea Monkeys are perfect for goldfish bowls.