Yea I was just reading about other jellies. That is good news that they dont all need cold temps. I am still interested in possibly keeping these. Here is more great info:
http://www.reefs.org/library/talklog/r_toonen_051798.html
WHAT SORT OF TANK SETUP DO I NEED?
It depends on the species which you intend to keep.
For Cassiopeia, you don't really need anything special. A large, well lit aquarium without a filter (but with an air-driven or gentle pump-driven water flow) seems to work just fine.
The medusae of Aurelia, on the other hand, are large and graceful attractions, but like all pelagic jellies, are built for the open sea, and are therefor poorly adapted to life in an aquarium.
There are many gelatinous species that are simply too fragile to ever be practical occupants in home aquaria, but many species are hardy enough that they can be easily maintained in an aquarium if it is specifically set up for them.
There are basically 3 designs that you can try depending on how much time and money you have to dedicate to your setup, how large the animals are, and how sensitive are the species you plan to culture. I will discuss all three of them in only brief detail here (we don't have time to get into great detail).
The first two are simple and cheap, but also pretty hard on the animals -- if you insist on trying to keep sensitive species, you should skip directly to the third option.
The first method is to use a simple hexagonal tank in which you set a large sponge filter (the larger the filter, the more diffuse the suction of flow through it) with an undergravel uplift tube covering the airline and the rising bubbles (if bubbles escape they can easily get into the swimming bell of the medusae and damage them or trap them on the surface).
The plastic uplift tube should end slightly above the water surface so that any water moved up the tube by the bubbles is dropped back into the tank, breaking the surface tension and aerating the tank. This will also help to push any jellies on the surface back down into the water column.
By running bubbles up the tube at the appropriate speed (a few per second) you should get very gentle turnover in the tank, but not run the risk of sucking all your jellies into the filter. I maintained a tank like this with a healthy tropical hydromedusa culture for about 3 years.
In the past, when I set up a jelly tank, I would simply use a very diffuse flow-through system to keep the medusae in suspension. One simple way to do this is to use a small canister filter to move water from one end of the aquarium to the other.
To do this you would set a spray bar across one edge of a large aquarium (say the left side) aimed toward the glass, and the intake at the other end of the tank (in this case, the right).
Then both sides of the tank would be sealed off from the central portion by hot-gluing a section of fiberglass mosquito mesh across the aquarium about 6-10 inches (depending on the strength of your filter) from each end of the tank (the more powerful filter you get, the more space you'll have to cut off each end of the aquarium.
Obviously, if you're going to "waste" 12-20 inches of your aquarium length, it had better be a long tank, so keep that in mind when the urge to put a large filter on your tank strikes you (I used a Fluval 103 pump on a 55 G tank - I have used tanks as small as 27 G, but wouldn't try to go much smaller than that).
The purpose of the mosquito mesh is to allow for undisturbed flow from the intake to the spray bar, but simultaneously prevent areas of high flow or suction that are likely to trap or damage the medusae.
The jellies can then be kept in the central portion of the tank because the flow through the mosquito netting is so diffuse that the medusae which contact it can easily swim away of their own accord.
There is also no reason that you couldn't keep other animals (that are stronger swimmers - such as seahorses, for example) on the ends of the tank, because any Artemia which escaped through the mesh would simply become food for either the jellies in the central portion or the animals on the ends of the tank.
In that way you could set up a very interesting display with smaller fishes on the ends of the aquarium and the medusae in the center, but keep in mind that you have a VERY small filter on the tank and need to keep the bioload down to maintain water quality!
This is basically the technique I and others have used to keep jellyfish alive for research purposes, but those tanks are almost always flow-through, so there was no need for the recirculating filter (natural sea water was simply pumped into one end of the tank, and drained back into the ocean at the other).
The final method is the most complicated and expensive, but also the most likely to succeed of all. You could build or buy a special tank designed to house your jellies in suspension at all times (called a kreisel).
These large circular tanks, which institutions like the Monterey Bay Aquarium use to keep their gelatinous zooplankton, are basically a large ring sealed between 2 flat panes of glass.
The ring has an opening along one side where water is piped through a thin tube slowly back into the tank, and a small overflow that allows excess water to dribble over the edge to a reservoir at the bottom.
A small pump, basically similar to a dosing pump, is used to deliver water from the reservoir back into the tank.
This constant flow of water, directed along the wall of the ring, causes a swirling current in the tank which forces the animals towards the center of the tank, and prevents them from either settling out of the water column or being trapped by the water movement.
This is a serious undertaking (you'll have to specially order or design and build your own tank if you intend to try this - although Dane Tullock was talking about posting a DIY design for a pseudokreisel sometime soon), and will probably not be a common sight in home displays.
There are many other methods that have been successfully used to maintain jellies, but I'm going to quit there
Jelly fish start out as polyps then they move into the medusa stage where they become the sexually mature adult that you recognize. They're close cousins to anenomes which are much less mobile. They have nemocysts to catch they're prey just like a anenome. Could you imagine a anenome swiming around your corals 24/7? Reef safe? I doubt it.
