In aquariums, jellies will grow according to the superiority of the animals. When keeping several jellies in a closed system, like an aquarium, the strongest jellies will emerge in the first two months and begin to get larger, while the others may grow more slowly or even start to get smaller. It doesn’t mean you are doing anything wrong in keeping them, it is simply a normal result of natural selection. Therefore, purchasing jellies that are significantly different in size makes for an uneven playing field when it comes to feeding. The larger animals you purchased will immediately outcompete the smaller ones, even though the smaller ones were originally just as strong.
Jellyfish in captivity, when maintained properly, will have a normal life expectancy of one year from start to finish. That being said, if you have a jelly that is 2” in diameter, it is already about 3 months old, so you will be able to enjoy it for about 9 more months. A jelly that is 3” in diameter is about 4 months old, and you will enjoy it for about 8 months, and so on. One year is one year—from the time of strobilation (the event where a jelly is “born”) to the time that it grows old and dies. So if you received it in January, let’s say, it is already 3 or 4 months old and will only live for another 8 or 9 months until September or October—not until the following January.
We always recommend initially purchasing jellies that are about the same size—within 1″ in diameter of each other. When jellies are more than 1″ apart in size, these competition problems can start to affect the smaller jellies.
If you start to notice a few of your jellies are shrinking, do not overfeed in an attempt to get them growing again. Feeding them more may seem like a solution, but it is not. The strongest animals will still win out over the weaker ones: the only thing you will be doing is compromising your water quality and the overall health of your setup. Please read more on our blog post about feeding and see some good examples of how much to feed. The best thing to do is simply let nature take its course and enjoy your jellies. Even though the strongest ones get bigger, the smaller ones will be just fine and simply exist “as is” in your system and give your tank some size diversity over time.
By now we all should know that the true key to keeping your jellies happy and healthy is maintaining stability in your tank. Stability is achieved after fully cycling your tank for 4-6 weeks. Once cycled, water changes are a good weekly maintenance practice because pH will gradually decrease and harmful chemicals like phosphates and nitrates can build up naturally over time, even in healthy systems. Beneficial bacteria and carbon filters in your filter box take care of a good portion of keeping your tank stable, but it’s important for you to assist in maintaining the water quality by performing water changes on a weekly basis. Be aware though, changing water is not a fix-all and when done in excess can actually harmful.
You should NEVER change more than 20% of your tank’s water volume at one time… here is why:
The ammonia level will spike after a large water change due to the beneficial bacteria dying off. This can leave you with hurt and shredded jellies. The bacteria die off because they are marine organisms, too, and when you change a large portion of their aquatic environment with that big water change, they get shocked and die. Therefore, no bacteria = ammonia spike = shredded jellies.
We recommend you change only 10% – 20% of your water once a week—no more!
It’s also good to check the parameters of your new water so you are aware of exactly what you are adding to your tank.
The point we’re making here is that water changes, although helpful, can be harmful if done in excess… like most things! 🙂
Relocating? Need some help figuring out how & when to move the jellyfish?
First, there’s a couple things to keep in mind.
Time is of the essence. As you know, your jellies need a constant current of water, so it’s not good to keep them out of their tank for more than a day. For the same reason, it’s crucial that your tank has access to electricity to keep the pump running, so you can’t leave it in your new place before the utilities are sorted out. This process needs to happen as quickly as possible to ensure the safety of your jellies, so it’s probably a good idea to save the jellyfish tank for the last day of your move.
Your filter media needs to remain submerged and in the dark the entire time. You spent a whole month cycling your tank’s bacteria, but it only takes a couple hours to kill them off again if you let your filter media dry out or expose it to sunlight for too long. Make sure you have something to accommodate your bio balls and carbon filters, for example a large, sealable ziploc bag or watertight tupperware container, and something to keep them shaded, like a drawstring bag or even just a towel to wrap them in.
Once you set the tank up, it’s hard to move. Make sure you already have the location picked out for your tank in the new house so you only have to set it up once. You may want to review this guide to choose the right place for your tank.
And here’s a list of the supplies you’ll need:
Buckets or tubs, one or two big enough to hold the water in your tank, plus another bucket for a few gallons of extra new saltwater
2-3 gallons of newly mixed/purchased saltwater to add to your system while you’re setting it back up
Large trash bags to line the bucket(s)
Zip ties to cinch the trash bags closed so the water doesn’t spill
Large ziploc bag or tupperware to store your bio filter media
Towels to keep you from ruining your new or old floors
Small cup for transferring jellies in and out of your tank
Level to make sure your tank is level in your new home
Alright, you’ve gathered your supplies, now you’re ready for the breakdown.
Photo by Pixabay on Pexels.com
Breakdown
Step 1: Prepare the jellyfish transition container. Line a bucket or plastic tub with a trash bag, and begin to fill the bag with a few gallons of water from your tank.
Step 2: Transfer your jellies out of the tank. Unplug your tank, and gently move the jellies from your tank to your bucket using a small cup.
Step 3: Take the filter media out of the tank. Take the bio balls and carbon filters (and micron pad if you have one) out of your filter box and place them in a large ziploc bag or tupperware container. Fill the container with tank water and seal it for transportation, then wrap it in a towel or put it in a drawstring bag to keep it out of the sunlight.
Step 4: Get the rest of the water out of your tank. Fill the jellyfish bucket the rest of the way up with water, then fill another bag-lined bucket with the remaining water until your tank is empty. Now cinch your bags closed with zip ties, making sure to get ALL the air out of the bags. This way they don’t slosh around or spill in your vehicle, and your jellies won’t be harmed by air bubbles.
Step 5: Dry the inside of your tank. Give the interior a good wipe down with a towel to make sure it won’t get the inside of your vehicle wet. You may want to leave a towel in the display area and a towel in the sump just to soak up any extra water on the drive.
Step 6: Pack it up. Keep the drip tray, soffet, and lid separate from the tank so they don’t rattle around and scratch the acrylic. You may want to wrap the tank in a moving blanket to prevent scratching or other damage.
Now you’re at the new place, so it’s time to set it all back up.
Step 1: Place your tank in its new spot. Make sure it’s level before you add water, but keep in mind it may shift with the added weight of the water. If it’s not level, wedge a shim underneath it in the right places until it is. Keeping your tank level is essential.
Step 2: Add water and filter media to the tank. Take the water out of your no-jelly bucket and put it back in the tank, then keep filling it as close to the top as you can while keeping at least a couple gallons of water in the jelly bucket. Add your filter media back to the filter box, preferably using a clean mechanical filter to catch any gunk that may come out of your spray bars when you turn the pump on. Now fill the remainder of the tank with the few gallons of new saltwater you brought, keeping an eye on the sump level so as not to cause an overflow.
Step 3: Turn the pump on and wait. Now your tank is ready to be up and running again, so plug the pump back in and let the water cycle through for at least an hour before you add your jellies back. There will probably be some loose gunk from the plumbing or the biological filters floating in the system, which you can simply allow the mechanical filters to catch over time, or remove yourself with a turkey baster.
Step 4: “Burp” the air out of your tubing. As you add water back, air bubbles will start to form in your tubing and in your spray bars, which can harm your jellies if they make their way into the display area of your tank later. Give your tubing a gentle shake to loosen some bubbles, then give it a gentle squeeze to help push the bubbles out. Now move your finger under the top spray bar and push the bubbles out from underneath, and repeat the process until they’re gone.
Step 4: Acclimate your jellies. Even though your tank has mostly the same water as before, the new salt water you added may create a slight change in water temperature and/or chemistry that could potentially harm your jellies if you just dump them straight in. So just to be safe, perform 3-4 small water changes [roughly a cup (8oz)] over the course of half an hour once the water in your tank starts to clear up. Then you can gently add them back to your tank one by one with the cup you used earlier.
Step 5: Welcome your jellies to their new home! Sharing cake and balloons with loved ones is encouraged, but not necessary.
Low pH can have adverse effects on moon jellyfish over time, especially when it drops below 7.6. This problem is common in aquariums with filtration systems that don’t allow for adequate aeration or disturbance of water.
The optimal pH for moon jellyfish is 8.0-8.2. As pH lowers below this range, the water becomes more acidic and harbors excess carbon dioxide (CO₂). If prolonged, the lower-than-optimal pH can cause pitting in the bell, eversion, and bell shrinkage in jellies. Although moon jellyfish are commonly described as being “hardy” and “tolerant” of extreme water quality levels, too extreme can and will eventually cause them damage.
A damaged jellyfish after living in <7.6 water. Photo from our Cubic Orbit 20 Aeration video.
Filters that allow for splashing and rapid movement of water through them introduces oxygen to the system, keeping the pH up by steadily off-gassing that harmful CO₂. When filters are completely submerged in water, the rate at which the water is moving through them is little to none and can negatively affect both the water quality of your aquarium and the beneficial bacteria that you’ve worked so hard to grow during cycling. If the water isn’t moving through the filters, then the filters are doing nothing to clean the water. Adequate and efficient water flow through the filters is necessary for both the water quality and beneficial bacteria to stay in tip-top shape.
Luckily, this is an easy fix!
There’s all kinds of water conditioners, additives, and buffers on the market today that are specifically made to raise pH… for normal fish tanks, however. Since jellyfish are 96% water, they are a bit more sensitive to the chemical makeup of water than normal saltwater fish. So, adding in a bunch of chemical powders and liquids, especially into a small desktop jellyfish aquarium with less than 10 gallons of volume, isn’t always the best idea and can cause more harm than good! So, don’t do it!
Instead, we recommend the following tips to help keep your pH optimal:
Adding a bubbler is an easy and worry-free fix to raise pH. Bubblers (also known as aerators) constantly introduce oxygen to the water via bubbles. Most aerators include a valve or dial to alter the rate of bubbles giving you more control, which is even better.
It’s best to place the bubbler in the filter compartment, away from the pump, and as far down to the bottom of the tank as possible. This way, the bubbles are not being sucked into the pump and have a longer path to reach the surface, releasing a bit more oxygen into the water.
Note: You do not need an air stone, if one is included. These will only create smaller, erratic bubbles that have a higher chance of getting sucked up by the pump and into the jellyfish area – which you don’t want!
Always make sure your new saltwater has a pH of 8.0-8.2. This will help raise the overall pH of your aquarium and keep it up through weekly water changes.
We experienced this problem when working with the 6 gallon Cubic Orbit 20 jellyfish aquarium, as you can see in the video below that we put together some time ago.
Despite what some conspiracy theorists might shout at you, tap water is generally safe to drink for humans. For jellyfish, on the other hand, it might as well be poison.
Tap water contains small amounts of metals and minerals that you and I can hardly notice when we drink from the sink, but even in small concentrations, these elements can seriously disrupt a small jelly’s bodily functions and cause them to shrivel and stop belling. This is why we insist that whenever you add saltwater to your tank, whether you’re filling it for the first time or performing a routine water change, you ALWAYS mix the salt with either reverse osmosis (RO)water or distilled water, and NEVER use water from the tap, no matter how nice your filter pitcher might be.
Same goes for bringing your salinity down with freshwater: ONLY use RO or distilled when adding fresh water to your system.
*** Side note: bottled water is not always distilled water. Your jellies don’t drink Dasani! Jugs of distilled water are available at most grocery stores, but beware as there will be various types of water. Be sure it is labeled only as “Distilled Water” and not “Spring Water,” “Purified Water,” “Mineral Water,” “Alkaline Water,” or anything else. ***
Additionally, if your system maintenance requires filters to be rinsed periodically, it is best to do so with old saltwater taken from your system during a water change, rather than just running it under the sink. Your tank’s beneficial bacteria don’t care much for tap water either, and you certainly don’t want to make them unhappy.
The same rule applies with your algae scrubbers and any other items you might rinse and stick back in your tank. ALWAYS give them a quick dunk in some old salt water or some RO/distilled water and allow them to air dry before you place them back in your system. Your jellies will thank you!
You might have noticed that no matter how many times you clean the sides of your tank with those magnetic algae scrubbers, there are just some parts of the internal anatomy of your tank that you’ll never be able to clean. Now some algae growth is normal and perfectly okay to have in any tank, but certain kinds in certain places can start to become a problem over time. Gunk from uneaten jellyfish food, bits of algae beyond the reach of scrubbing tools, and all sorts of unidentifiable crud can start to build up in your system and gum up the works in ways you may not notice until it’s too late.
But never fear! There’s a solution to these invisible clogs, and you only need to do it about once a year! Bleaching and Dechlorination.
The first thing you need to know about this process: It is absolutely lethal to anything and everything that lives in your tank. That means anything you want to survive this cleaning needs to be kept separate from your system the entire time. That means not just your jellies, but anything that has helpful bacteria on it. Filter pads, carbon bags, bio balls, all of it needs to go in a separate container with some saltwater until the system is ready to start up again.
The next important aspect of the deep clean is that it takes some time. About three hours to be specific. Now, this isn’t all hands-on, can’t-step-away-to-check-your-email time, but you don’t want to rush the process too much and have it all be for nothing.
Now essentially what you’re doing is running the bleach solution through your system to eat away all the unwanted algae and gunk, then using the dechlorinating solution to neutralize the bleach so your system will be safe enough for your jellies once it’s clean, and finally, sucking out all the dechlorinated gunk water until your tank is good as new.
For a detailed description of the process, check out page 7 of your EON instruction manual, or email our customer support team at moonjellyfish.com@gmail.com if your manual seems to have misplaced itself.
If they do, I’m sorry to hear that, but don’t despair just yet. Once you determine the problem & fix it, the jellies can bounce back and repair themselves in no time! Here are the top 5 reasons jellyfish will start to fall apart…
1. Improper filtration and/or incomplete cycling of your filters.
2. Ammonia spike.
3. Not Acclimating your Jellyfish Properly
4. Improperly making up your saltwater
5. Heavy metal contamination.
1. Improper filtration and/or incomplete cycling of your filters.
If you haven’t properly cycled your tank, then you most likely have toxic levels of ammonia and/or nitrite in your water. This can happen when you initially set up an aquarium and add jellyfish (or any life forms, for that matter…this is not a jellyfish specific issue, but a standard fish or coral tank issue. You must take the time to properly cycle your aquarium no matter what animals you choose to keep in it). Once jellyfish are added to the tank, they begin to produce ammonia. Once ammonia starts to build up, you need to have a way to eliminate it. This is why proper filtration is important. A properly filtered aquarium will have a biological filter in place, which will remove the toxic ammonia and nitrite by way of the beneficial bacteria that populate the filter media (i.e. bio balls). If you do not have beneficial bacteria actively removing the ammonia and nitrite, then the water becomes toxic and the jellyfish will soon begin (within 2 days) to disintegrate like the pictures demonstrate.
Ammonia & Nitrite levels demonstrating the middle of a nitrification cycle. This is a very toxic situation. Jellyfish will fall apart if subjected to these levels of toxicity.
2. Ammonia spike.
Why are you having an ammonia spike even after you’ve already cycled your tank? An ammonia spike can occur if you stopped feeding your tank for any reason. Sometimes folks let the aquarium go down, or let it run without any animals in it for awhile like if they go on vacation or take some time away from keeping jellyfish, or they don’t have jellies in it for several days for whatever reason. This leads to an ammonia spike because your beneficial bacteria in you filter box didn’t receive any ammonia to eat—your system wasn’t creating any ammonia because you had no jellyfish in it & subsequently weren’t feeding any jellyfish. This means the beneficial bacteria went with out food (ammonia) and starved to death. So, if you then add jellyfish to the tank when you get back from vacation (or whatever), there is no beneficial bacteria available in the filter box to eliminate the toxic ammonia & you experience an ammonia spike and shredded jellyfish as the pictures show.
If you do go on vacation, or take more than 3 days away from having jellyfish in your tank, you can alway place a small, 1/4″ piece of raw fish or shrimp in the filter box to continue to decompose and create ammonia for the beneficial bacteria to feed on while you’re away. When you return, always take an ammonia reading and remove the piece of raw fish or shrimp before adding new jellyfish to the tank. Make sure your ammonia and nitrite levels are at zero before acclimating any new jellyfish into your tank.
An ammonia spike can also happen if you interrupted the cycling process by cleaning the tank, changing any mechanical or chemical filters, or conducted any water changes prior to the tank completely finishing its cycling process. Do not interrupt the cycling process. I know it’s tempting to want to get the sides & bottom of the tank clean. The algae growth can be unsightly, but remember, you are creating a living environment from a static one. Life can be messy! Let nature take it’s course and be patient– I know it’s hard, but it is necessary. You can clean the tank all you want after the cycling process is over! If you interrupt the cycle, it can take almost 3 times as long to get it back on track an in a non-toxic state. Be patient. It’s worth the wait!
3. Not Acclimating your Jellyfish Properly
You are receiving jellyfish that are coming from a pristine environment. When you receive a shipment of jellyfish, the water quality parameters are most likely different from yours. You must take the time to acclimate the jellyfish in the shipping bag to the temperature of your system. After 10-15 minutes of floating the bag so the temperatures equalize between the bag and your tank water, acclimate them to your water quality (pH, salinity), by conducting small water changes in the bag over 45 minutes to 1 hour. Don’t take all night doing this step. The jellies need to get out of the bag and into a moving environment. Acclimation shouldn’t take more than 1.5 hours from start to finish. If it is taking longer than that, then there is another problem at hand that needs to be addressed.
4. Improperly making up your saltwater
If you are making up your saltwater with tap water, your jellyfish will fall apart. Tap water has heavy metals in it that the jellyfish cannot tolerate. You must make up your saltwater with RO, RO/DI, or distilled water for it to be safe for jellyfish, much like a reef tank.
If you are not aerating your saltwater for at least 24 hours in a bucket with a small submersible pump, then you most likely are adding undissolved salts to your tank. The jellies don’t do well with undissolved salts. Please read our blog post that covers this topic in depth: “Problem with Your Jellyfish? Undissolved Salts Could be the Culprit”
5. Heavy metal contamination.
Do not use metal utensils or tools with your saltwater jellyfish aquarium. Only use plastic tools. Always wash your hands before dealing with your jellyfish or handling the jellyfish food. Zinc, brass, lead & petroleum products (sometimes found in soaps and lotions) will add heavy metals to your system. The jellyfish will fall apart if you introduce them into the water. Also, I should mention that aquarium heaters can get old– moreover, their seals can get old and crack. This can allow water to leak into them where the metal heating coil is located and other metal parts. If you have an old heater, check it for any visual signs of rust on the heating coil. If you see rust, throw it away and purchase a new one.
Send us your problem jellyfish pictures and we’ll diagnose the problem and tell you how to fix it. We’ll also write a new blog post about it so we can inform and help others that may be experiencing the same problem!
Send your pics to moonjellyfish.com@gmail.com
•••
Have you had an unusually long cycling process? Are your new jellyfish shrinking fast even after the tank finally cycled?? Please read our blog post next week for answers.
All hobbies start with overwhelming enthusiasm! We are so eager to learn all that we can about whatever it is, then buy all the necessary gear and equipment (most hobbies have the coolest gear and accessories to go along with them!) and dive right in with all the excitement of a 6 year old on Christmas morning! These are the things that make hobbies so much fun! They are generally new to us and open us up to all kinds of new ideas and people, places and things. Your budding hobby has you jumping out of your shorts and you just don’t want to wait another minute to get it completely mastered.
Some hobbies, however, do require some patience – at least at the beginning stages. Gardening is one of those hobbies. You can’t plant your seeds or seedlings one day and then go out the next day or following week and dig them up to replant them because you think they are not growing fast enough. This will surely inhibit their growth, if not kill them in the process. Plants have roots that need to establish themselves in the soil before they can send nourishment to the plant for growth. The soil & roots need time to go through a nitrogen-fixing cycle, or nitrification cycle. It is a natural activity in which nitrogen is processed by bacteria in the soil in order to make it available to the plant for nourishment. This cycling process is also necessary in marine environments in order to create a safe and non-toxic environment for your fish and /or invertebrates. Without the nitrification process completed in your system, you will not be successful at keeping anything alive—it’s a fact.
Patience is needed to allow the beneficial bacteria to populate your biological filters. Generally biological filters are a darkened area like a filter box where no light enters. Bacteria are inhibited by light so a filter box is best for housing the biological filter. It is also an area that will not be disturbed during maintenance because we don’t want cause a bacterial bloom in the aquarium. Once they are established, your biological filters are the foundation in which your hobby can begin.
So, remember these bacteria populations need a lot of food energy to grow so you don’t want to take away any of the ammonia producing elements in your system. The dirty filters, the detritus on the bottom, the slightly cloudy water—these are food producing (ammonia producing) and are just what you want to get those bacteria populations growing! Don’t do any water or filter changes (mechanical or chemical) during the cycling process. You will only be prolonging the cycle by diluting the food source for the bacteria.
This is not a jellyfish specific task. This is what every aquarist—hobbyist or professional, has to deal with all the time. But, once completed properly you can feel confident you have taken the necessary measures creating a safe and healthy home for your new pet jellyfish.
moon jellyfish blog 
