haha yeah. jellyfish are actually very beautiful animals. Basically, the two most critically important factors to take note of when rearing them is the tank stucture and diet.
1. Tank. Most jellyfish are unable to pulse themselves up all the time. Eventually, they will sink to the bottom if there is a lack of current. When they sink, they will almost always die. As such, a very special tank is required to keep them. This tank is the kriesel tank. There are many modifications of a kriesel tank and most of them work just as well. This egg yolk is living in a pseudokriesel. Im planning to rear sea nettles in a kriesel tank. I will post a picture of my kriesel tank asap.
The catch is this: Although a current is needed all the time, they MUST be kept away from suction as they will result in a gelatinous blob of lifeless protein. Solution: the kriesel tank.
2. Diet. Jellyfish usually have a very specific diet. In the wild, they feed on wild zooplankton or even other jellyfish. In the aquarium, the brine shrimp (newly hatched) is an okay substitute. They must be substantiated with more nutritious food occasionally though. For example, the egg yolk jellyfish will always show stunted growth when their diet lacks other jellyfish.
Other kind of jellyfish, the more common blue jelly (Catostylus sp.) also require strong light as they have zooxanthellae just like some corals. Feeding is needed too.
One exception is the upside down jellyfish (Cassiopea sp.) where they simply require very strong light and a tank with LOW current and kept away from suction. Feeding is minimal as they obtain most of their nutrients from the zooxanthellae symbiosis.
I will post some pictures of my upside down jellyfish tank soon.. I bred them and there are about 100 plus jellies now =]
hope this helps =]