How to Breed Moon Jellyfish

Breeding jellyfish overall, seems like a very daunting task. Jellyfish have a very strange life cycle and spend whole portions of their lives as microscopic or minute organisms.
       However, with proper instruction and technique, breeding jellyfish can be very possible. Jellyfish can even be bred in the confines of your home.
        First lets discuss the life cycle of moon jellyfish. this cycles is pretty consistent with other jellyfish although some species have different means of reproduction. IE box jelly, crystal jelly etc. We will stick with the moon jellyfish lifecycle here.
As you can see in this diagram the mature jellyfish produce eggs via sexual reproduction. These eggs are released into the water by the female, once fertilized by the male.

Then the egg develops into a microscopic ball of cells known as a planula. These planula will swim around in the water, using cilia to propel themselves. Evntually, around 7-10 days, the planula with settle on a hard surface and grow into a polyp.

The polyp will gather food using its tentacles and bud off to asexually produce more polyps. When the temperature rises and iodine levels increase the polyp will develop into a strobila.

Strobila are stacks of undeveloped baby jellyfish, known as ephyra. The ephyra at the top of the stack is the oldest and most developed. Once this ephyra develops enough, it will began to pulse and will pulse off the stack. This will happen with the rest of the ephyra on the stack and the polyp will return to its normal self.

These free swimming ephyra will grow and develop into small jellyfish. And eventually will grow into an adult jellyfish, also known as an adult medusa. Then the life cycle will repeat itself.

So theres the long and complete life cycle. Its rather interesting compared to other life cycles. So how do you breed these jellyfish? Well you may not even have to experience several of the life cycles stages. If you own several moon jellyfish then you may begin to find polyps in your jellyfish aquarium. Why you may even find ephyra on occasion. If you have ever visited a jellyfish aquarium at a museum or public aquarium you may notice several small jellyfish that have been bred naturally in the tank, escaping detection from the aquarium owners. This could occur in your private tank as well. However you may find yourself without jellyfish or with only one gender of jellyfish. but alas, you can still breed jellyfish!

Obtaining your Jellyfish or polyps--

It is most common for breeders to start at the polyp stage of the life cycle. Polyps are small but visible and reproduce to keep their own population alive, thus making them very stable. They can be transported, shipped, and sold relatively easy as well making them a great place to start.

However you must obtain your polyps from somewhere. Perhaps there are polyps in your tank. In that case scrape or suck a few off and put them in a covered dish, culture dish, petri dish, small aqaurium etc. Just make sure that they have room to bud off and enough water to prevent fouling in 24 hours time. Leave the polyps in their vessel, covered, to prevent the water from, evaporating and altering salinity. Moon jellyfish polyps should be fine in room temp although an incubator/heater can be used as well.

If you don't have polyps then you are going to have to buy some from a dealer of jellyfish or grow them from planula. Buying them is easiest but can be expensive and unpredictable due to stocking issues. However growing them from planula isn't very easy.

To grow polyps from planula, you can do two things. Buy some jellyfish and suck planula from the corners of the shipping bags. Planula seem to collect in the corners and can be sucked up via turkey baster, however planula are too tiny to see. You can also dissect gonads out of several jellyfish and put them in a dish together. Use whichever method suits you the best. Anyways, once you have confirmed you have planula by checking for them under a microscope, you can grow polyps. To do this either dump your planula in a proper jellyfish tank or put them in a dish. Cover the dish and wait 7-10 days before bothering them whatsoever. Check every so often to see if there is early polyp development. once the 7-10 days is up check for polyps again, don't remove the cover yet. Of there is no sign of polyps give it 5 more days. you should have polyps by then, otherwise you have a dish full of dead planula. I find the putting planula in a jellyfish tank works really well since you have water that is temperature controlled and you have a set up environment, providing food, waste removal and other important aspects that are hard to achieve in a dish.

However you have obtained your polyps you can know pat yourself on the back for possible getting through some very hard stages. Now all you have to do is get those polyps to produce jellyfish. However we need to think ahead first as this will drastically determine whether or not your jellyfish will live. First where are your polyps living? If they are living in a dish then you are safe. If they are living in a tank then you must proceed with caution. When polyps produce ephyra in a tank you may wake up one morning and find hundreds of ephyra in your tank!!!

What are you feeding the polyps and what will you feed the ephyra? I always feed my polyps and ephyra live decapsulated brine shrimp, as well as liquid invertebrate reef food (found at petco/petsmart). You must use decapsulated brine shrimp, as regular brine shrimp eggs will foul the water and introduce foreign organisms into your tank or cultures. these will most likely kill your polyp or harm them in some way.

What do you plan to keep your ephyra in? I like using petri dishes and glass cups or tuppaware containers. Flow isn't necessary for ephyra but you will need to change the water every day. If you own a small kreisel jellyfish tank you may be able to keep ephyra in there but its likely that they will be blended up. its best to keep them in a dish or container with still water. Feed them daily and change their water daily.

Now that we have covered our preparation we can cover how ephyra are produced. When a polyp senses high levels of iodine and an increase in temp, it will begin to make those stacks of jellyfish. You must coax them into doing this by raising the temperature in your tank up a few degrees or if you have polyps in a dish you can add 1-2 drops of lugol's iodine or perhaps invertebrate food that contains iodine. Your polyps will begin to form stacks of 5-12 ephyra. The ephyra will develop and pulse off. Congrats if you have gotten this far!

Now you must raise these ephyra to a sale-able size or big enough to keep as pets. These ephyra aren't really big enough to keep in a jellyfish aquarium. I personally prefer to keep my ephyra in a large 8 inch dish on a magnetic stirrer or in a breeding system. The dish method is very good for those who are starting out and want to raise just a few jellyfish at a time to put in their tanks. The breeding systems can raise many more jellyfish at a time.

Dish Method- You will need an 8 inch diameter culture dish and a magnetic stirrer. Ephyra go in the dish with a stir bar. Set the stirrer on one of its lower settings. The ephyra should be floating around in the dish, and not sitting in one place. For moon jellyfish; its okay if the ephyra drag along the bottom every now and then. Feed baby brine shrimp and change water daily.

Breeding System- A jellyfish breeding system consists of two tanks and a filter. The first tank will be a polyp tank. Polyps are grown in here. Water should flow in from one side of the tank via and inlet hose or pipe. A bulkhead should be installed on the opposite end. Water will drain out of this bulkhead and into the ephyra tank. They ephyra tank can be nearly identically, but must have a screen glued in. Glue a 500 micron screen about and inch to an inch and half away from the bulkhead drain. The bulkhead will lead to filtration. Your system should now look like a two tier fountain. As polyps strobilate, ephyra will get picked up and will drain into their tank. The screen keeps them in the tank. Flow from the polyp tank should ensure that the ephyra stay in circulation. The jellyfish can grow out in their tank or can be moved to a different tank to be grown.

A moon jellyfish successfully grown in a 10 gallon DIY kreisel. 

This was a brief description. For a full guide on building the ephyra tank check out this

     A moon jellyfish polyp growing in a jellyfish tank. 

A small polyp. 

A small strobila growing in a petri dish. 

A newly released ephyra lingering in a petri dish.

Widmer, Chad. How to Keep Jellyfish in Aquariums. 1. Tuscon : Wheatmark, 2008. 192. Print.

"Aurelia ." Generalized life cycle of scyphozoan jellyfishes (e.g. Aurelia) . Web. 23 Aug 2011. <>.