My cat almost jumped INTO the tank..
I have a flat glass hood, so its pretty much invisable.
She would jump up there when she hears a noise like a fish skirting or my fillters picking up sand.
And i would put the glass hood somewhere else while filling the tank, and she jumped up thinkin it was there.
Man is she fast, she balanced her him on the rim of the tank with her back legs with her paws nearly touching the water.