Um... If it was in August, what holiday then?

I mean, I did suggest the ghost festival, and most of the time it does fall on August. But there isn't actually a fixed date. The chinese calender is completely different to the western calender, so it's going to be hard to prepare and time it... And actually, it isn't really a fun festival. People under the age of 18 don't normally participate (don't ask why).

Days of the dead holiday maybe?

Days of the dead is similar to celebrating Halloween. I doubt that will be celebrated by Res unless they move the Jakkus to the the days of the dead.

By similar, I mean that the dead in one way, is celebrated along with many other ghosts and ghouls on Halloween. Both celebrations are different, but they basicly are the same thing in one sense.

But it would be fair for a water based holiday to be celebrated on Aquati with a creatu.