What is the best way to secure an aquarium top for a hamster?

I would say use some of the gripping shelf liner to help secure the tank to the table and make it much harder to push, then put a book or two on the lid. Another trick is to place a mouse trap or two on the lid just ready to go off. Then if your cat bumps the tank or the lid the mouse trap will snap and make it's loud noise and scare the cat. Once or twice and the cat will get the message not to fool wth the tank any more. And no, I don't mean so the traps will hurt the cat people.... just to scare it.

MM

they make topers for the aquarium for hamsters, it has the tub holes on it and everything, i had a huge maze system going for my hamster as a kid, also in regards to the first responder, if hamster are only suppose to be in open air cages then why do they make aquarium type hamster houses, specifically for hamsters, i had a few of those and the tubes ran into each, my hamster was set lol bigger house then i had lol

they make clips for screen tops, so its hard to get it off the tank. I have some hamsters and a cat that likes to eat them. I keep clips on most of the tanks, and sometimes a nice big piece of slate does wonders..

Well put the tank up high! or put it in a room with a lock on the door and lock it when the cats around, get a mesh lid too.

you really ought to have a proper cage for the hamster...glass aquariums are NOT proper cages for hamsters, rats, gerbils or chinchchilla's...they need open air type cages...with mazes, things to do like run all night, toys, food, water in a bottle...and keep the cat out of the room with the hamster...to the cat a hamster is a toy/food and will always go for it....if you love the hamster keep it safe....and well cared for....

you can set something on top, and put like bookends on either side 2 keep the cat from pushing it

and like mm said below, something to grip the bottom, like what you put under rugs

use a rock on top of the lid to hold it down, or a couple of books/magazines.