Compared to fish , birds are far more difficult to keep at home, because some bird stealing gangs are very active , breaking into homes and stealing the bird . They also find it difficult to adjust to a new cage , and are often very quiet for the first few days.
Cats are also not targetting fish, they mainly target birds, even though the bird is kept in a cage, there are instances when the cat opened the cage and ate birds. So it also important to ensure the room where the bird cage is kept is cat proof and no cat can enter the room.
Compared to fish, birds take a longer time to adjust to a new cage. Again other than the bird sellers, there is usually no one who can provide any information on the birds when ill or new to a cage. Bird flu is a disease connected to birds which was widespread some years ago