I would really like to know if jelly fish could be kept by human beings as pets.

I suppose if you had a large enough tank and all the equipment to keep the water at the right levels.

A salt-water tank, at that. Not an easy thing to keep balanced as needed. And, jelly fish catch smaller fish to eat by poisoning them with tiny needle-like organs located in their tentacles. You may not want to try to pet any 'pet jellyfish'. They are rather interesting, but are probably better appreciated in their natural surroundings.

Paleophlatus is absolutely right. I had a salt-water tank for a couple of years, and my daughter and her husband have a truly beautiful one right now, but it's a very expensive and difficult process to maintain one. I had a mostly invertebrate tank with jellyfish as occasional members of the community, but you can not handle them unless you know what you're doing. Getting stung is painful.

An octopus, on the other hand, is much more amenable to "pet" status. They need to live alone in a tank, which makes the tank smaller and easier to maintain, and they can (they might not, depending on the individual) be very social towards humans.

Again, like Paleophlatus, I think you can probably find a more suitable pet and leave the sea creatures to the experts and to their natural habitat.

I have a hard enough time maintaining my 20 gallon fresh water tanks! Lol I couldn't imagine having an octopus, but I have seen the very small ones sold in our aqua-etc pet store. They look very fascinating, but I can imagine they would be very high maintenance.

Aurora, my intro to octopi as pets came from a random encounter at the Salt Water Fish Emporium I haunted back then. She told me that she'd bought an octopus and one of those octagonal tanks, set up a habitat, and had it positioned behind her living room sofa. She said she was watching TV one night and got the feeling (you know how that is) that someone was behind her. She turned around, and it was her little octo with his front tentacles over the edge of the tank, watching TV with her. She changed the channel to see what he'd do. Turned out he had very specific tastes! Action shows made him turn black, grow horns, and scoot back into his cave. Musical and less-noisy shows made him come back out and turn nicer colors and watch for a while. Isn't that fascinating? Since it's only one to a tank (so there's no "inking" in stress), the care is apparently easier than a tank full of fish and invertebrates. Who would have thunk?

Very cool!