I would love to see a cloud fish. Perhaps similar to the ghost shark, it could be really fluffy with swirls spaced periodically. The name could be Zephryus fish, as reference to the god of west winds in Greek mythology. This would then obviously mean it could be found at ponds in Aquila. Probably an ice fish as well.
I would also love to see a snowman fish! Maybe similar to the Christmas seasonal fish, this fish would have maybe two or three spheres for a body with coal eyes. Maybe a cute striped scarf to complete the look. The name could be as simple as snowman fish. This would obviously be an ice fish as well.