tell your cousin to get a proper tank, some pretty live plants, and plant them in the vase IN the tank. usually people who do things like that don't do them out of carelessness but because they don't know their "creative" idea is hurting their fish. give them a way to incorporate their idea into a proper home, and they have the satisfaction of knowing their creativity is still a part of their fish's home.
So remember, when you're feeling very small and insecure,
How amazingly unlikely is your birth,
And pray that there's intelligent life somewhere up in space,
'Cause there's bugger-all down here on Earth.
Loki/Grendel/Gail/Beowulf/Camilla/River/Bathory/Arwen/Lafayette/Deb/Jack Skellington (soon)