You can use the adjective piscine to describe anything that has to do with fish, from a piscine feast to the piscine inhabitants of a coral reef.
The Latin word for fish is piscis, and both the word piscine and the astrological sign Pisces come from this root. Like Pisces, piscine is pronounced with a long i sound in its first syllable. In French, piscine doesn’t mean “fishy;” it means “swimming pool.”
of or relating to fish