I pet jellyfish before and they are beautiful creatures. I don't have them now because of moving. I want to share so that more people will keep them as pet. Plus they are awesome and look fantastic especially when you are stoned. They are relativity easy to keep (difficult at first) and I highly recommend jellyfish as pet.
Things you need:
1. A jellyfish tank- You'll need a tank that can properly create a nice even flow for the jellies to swim or bell, and a safe guarded drain so they won't go down. You can either make one or buy one. I got mine from Jellyfish Art.
Some tanks require you to change water regularly (like Jellyfish Art one) and some don't (like Orbit 20). Depends on your budget you can get whichever that suits you.
2.Accessories- You'll need to change/test water regularly to make sure the pH, ammonia, nitrates and nitrites are within the range. So a test kit for those elements is needed. Also you'll need hydrometer, feeder and some cleaning accessories, usually these are given when you buy the tank.
3. Water- This is the most important part. Jellies are very sensitive to the water condition and temperature. If they start to look abnormal, the first thing you want to check is water. Companies suggested to use reverse osmosis salt water or distilled salt water (can get them from an aquarium shop).
I used deionised water and made up the salt water myself using marine salt. If you don't have any, it's ok, I've seen people using bottled water and their jellies were fine.
4. Jellyfish food- You can buy commercial jellyfish food or using brine shrimp. I strongly suggested to use brine shrimp. Brine shrimp contains more nutrient than jellyfish food. They can make your jellies grow faster and stronger.
You can purchase brine shrimp eggs online. How to culture and harvest them is really easy. Instructions how on to breed them usually mentioned on the selling page.
That's all you need to start your tank running! You need to run the tank without jellies for at least 12 hours and have the right level of ammonia, nitrite and nitrate.
Now you can catch jellyfish yourself or get one online!