piscas : fish
The Illunse word for fish (nominative plural) is piscas. Piscas means flashers, as in flashing lights, in Portuguese.
Fish (plural) in Latin is piscis. Fish (plural) in Old English is fiscas.
Fish (singular) in Illunse is pisc, which is a mix of the Latin word (piscis) and Old English word (fisc).
I think this Illunse word is somewhat guessable. In astrology, Pisces, is the sign of the fish.
Here's a link to my previous post, Fish, in J.R.R. Tolkien's words.