Cats and rodents
Cats have been programmed for hunting mice and rats, and they should never be trusted if rodents are nearby. Small mammals always have to be kept in a cage, preferably in a room where a cat is not allowed to enter. If this is not possible, make sure that the curious cat cannot damage the cage or open the door.
Cats and birds
Keep away smaller birds, that are in cages from cats and make sure that the cage is strong enough to withstand a determined attack. For their part birds can be scared at seeing a predator who is staring at them. If it is at all possible, keep the cage in a place where the cat will not see it.
Cats and reptiles
Large snakes such as pythons can be dangerous for cats, while smaller ones such as lizards can be at risk themselves. Always keep cats and reptiles away from each other.
Cats and fish
Make sure that your cat has no easy access to the aquarium, and protection covers are used. A properly protected aquarium can even be a source of harmless entertainment for cats, like TV is for humans.