Sephy was only allowed to stay up there because she's the smallest cat in the house. (Normally she isn't supposed to be up there either, but she looked so cute I couldn't resist leaving her alone to see what she'd do.)
It's possible the fish may have even been teasing her. More likely begging, though.
(Yes, the tank needs a water change; we're coming off a round of medication and since whatever Shubunkin had is finally clearing up, apparently on its own, I didn't want to upset whatever balance was reached.)