You can also try Aluminium foil on the lid. I hear they don't like that material.
Lol. That is amazing! I am no longer worried....Yay my two favorite types of pets can live in peace!I am a cat nut and fish/Betta nut...lol....I have 29 cats and 18 aquariums (not counting the small tanks) All or most of my aquarium are open top-my cats use some of the tanks to drink from and love to sit on the big filters I have on my big tanks to drink and watch the fish. I have never had any problems with the cats catching any fish from the tanks and the fish follow them around. I think the cats might feed them...lol...When the cats drink from the tanks I think they might drop trapped kibble bits in the tank and now the fish associate the cats with food...lol....It funny watching all the fish gather at the top when a cat approaches-drinking and sticking its paws in the water-especially on the lower rack with a tank full of Betta juvies. I have watched the fish jump and hit them a few times and the cat runs away-wondering what just happened...lol....
The only problem I have had with cats and tanks-is the cats knocking a small tank over. This has only happened a couple of times.
On one they knocked over last year-I didn't find it until nearly 8 hours later and oddly enough the Betta was still alive and even went on the spawn a few weeks later. I don't normally name my fish since I have so many-but this guy was named "Lucky Hairy" since he was lucky and covered in cat hair....lol.....