A 4" Poly is a LOT like the size and shape of a jumbo prawn... Just sayin... That would be a bummer to come in one day, and only see the ray in there. Not that it would be a bummer to be able to look in on a Ray (they're illegal for import here in Nevada... Prostitution, Gambling, 24hr. drinking- Fine, but ABSOLUTLY NO STINGRAYS), but it would be sad to lose a Poly to one.