If you want something to take care of and you don’t have much time, I would go with a fish but even that involves time in terms of cleaning out the aquarium and water changes and making sure the levels are right. But you can get away with a simple setup.
However, if you want something that is going to need some attention and interaction from you, then all the other pets require that from you. It’s a misconception that getting a rabbit or a bird or a guinea pig is going to be really hands-off because all those animals require attention and interaction to live their best lives.
More information about how to care for your fish can be found here.
Rabbits make great pets, they can be litter-trained. House training is also quite simple with a rabbit. They are interactive with us and they can be quite affectionate too. They can do really well living inside.
The worst thing to do with a rabbit is lock it in a hutch, they need free space, they need to have exercise in a bigger area and they need to have contact with other people or another rabbit if your rabbit is suitable for that. But you need to be careful because they can obviously chew things.
More information about how to care for your rabbits can be found here.
Guinea pigs are also lovely. They do really well living with at least two guinea pigs. They are quite social with each other, and they don’t tend to need as much space as a rabbit to exercise but they also need time out of an enclosure for exercise and stimulation.
More information about how to care for your guinea pigs can be found here.
Birds can be fantastic but they are clever and can be very demanding and prone to behavioural problems because of people not giving them the time and care that they need. You certainly can’t lock a bird in a small cage and just look at it as an ornament.
They are very social animals, they are very clever and very aware and they really need exercise around your home and enrichment in their environment to thrive.
More information about how to care for your birds can be found here.
Native wildlife is a tricky one. Ideally, they should be in the wild and that's why we have organisations like WIRES and various other rescue organisations that work to rehabilitate these animals and get them back to their natural environment.
Keeping them as pets with the right permits if they can’t be released into the environment is one of those topics that's out for debate but the first point of call, if a native animal doesn’t seem to be well, is that you need to call your local wildlife organisation.
There are definitely restrictions around what you are allowed to own as a pet, and things like reptiles require permits. The reason for that is that these exotic pets often require things in their environment and food that most people are not going to be well equipped to deal with. They have very specific needs.
More information about when and how to obtain a license to keep a reptile as a pet in Australia can be found here.