Most cats hate getting wet, but the sight of moving fish can prove to be too much for them to resist. When your fish see paws dropping into the water from the heavens and trying to swat them, the fish can become stressed or even injured. Stopping your cat's plans requires blocking his access to the water.
Step 1
Add a hood to your aquarium. Hoods not only keep little paws out of the water, they also keep your snails, frogs and other aquatic life inside their habitat. Avoid using glass hoods that are not made for your specific tank. The glass can crack if it does not properly fit and your cat decides to make it his new perch.
Step 2
Thwart your cat's access to the tank by blocking his path. If your cat prefers jumping to a lower fixture and then onto the fish tank, place a few stuffed animals, books or other objects in his way so he can't make or even attempt the jump.
Step 3
Place masking tape sticky-side-up on both the hood and the fixture that serves as his jumping pad. Cats don't enjoy having tape stuck to their paws and will make a move to vacate the platform when they encounter the stickiness. The downsides to this method are that it's not aesthetically pleasing and that stubborn cats will ignore the tape.
Step 4
Cover the back holes with plastic, tape or aluminum foil. Even with a hood, the back of the tank is partially open to allow room for accessories such as heater cords and filter parts. The holes are large enough that the placement of these accessories does not cover them completely. Your cat can stick his paws in the opening on the days he wants to go fishing, so cover them.
Step 5
Throw a towel or sheet over the tank at night. During the day, you can usually catch your cat in the act fast enough that he doesn't cause harm to your fish. At night, he has free reign of the house. Covering the tank with a sheet or towel kills his interest, because there's nothing moving to look at. Plus, your fish will appreciate the darkness.
Step 6
Close off the room that has the aquarium, if possible. As a last resort, you can block off your cat's access to the room if the room allows it. Try all other remedies first, as opening and closing the door will be a chore for you if you're in and out of the room several times a day.
