Jellyfish are strange and very foreign creatures. They’re often compared to alien spacecraft, and deservingly so. Unfortunately, these enigmatic creatures don’t have brains or mouths to tell us when they’re upset. As jellyfish guardians, we have to be able to tell the difference between a healthy jellyfish and a sick one.
For this post, we’re going to be using the Moon Jellyfish for all of our examples. Other species may vary slightly, but should be very similar.
What does a healthy jellyfish look like?
A healthy jellyfish should have an even, round bell. Their bodies should be fairly thick, and smooth. A happy moon Jellyfish will have hundreds of tiny fringe tentacles at the edge of the bell, and four mouth arms in the center. It should pulse once every few seconds.
In the above photo, notice how there are tons of long, hair like tentacles at the edge of the bell. These “fringe tentacles” are a good indicator of health. They should be long, relaxed and flow smoothly as the jellyfish pulses. They do tend to retract these while eating, so don’t be alarmed if they temporarily disappear!
Also notice the width of the bell. This is exactly how wide a healthy Moon Jelly should be. Thinner ones are less nourished, and may not be getting enough nutrition.
Note that the bells are round and very smooth. The jellies maintain a sort of half circle form. They aren’t thin like plates, but also aren’t balled up into a sphere. Both extremes are bad signs.
We hope this post can be used as a reference guide for your own jellies at home. Stay tuned, as our next post will be on common jellyfish ills and ails.
At the Jellyfish warehouse, we put the highest level of effort and research to create happy and healthy jellyfish for the home aquarium. You can purchase your own here: Jellyfish Warehouse
Comb Jellies are a fascinating and captivating sea creature. Their beautiful light-show of colors draws the attention of crowds . These odd jellies appear to almost be living spaceships, with colors pulsing up and down their bodies. What are these beautiful weird things and how do we care for them?
Comb Jellies are Not True Jellyfish
We often refer to these guys as “jellies” and not jellyfish because they are not actually true jellyfish. They are actually considered Ctenophores (ten-oh-fours), which is a group of stingless marine creatures. That’s right, they have no ability to sting whatsoever. Unlike Moon Jellyfish, which have very little sting, Comb Jellies substitute sting with sticky tentacles. Think about those sticky hands you would buy in a quarter machine as a kid. Comb Jellies also lack that characteristic pulsing motion that jellyfish have. Instead, Comb Jellies use eight rows of combs, or rows, to bat their way through the water. These combs beat back and forth quickly, and allows the jelly to hover, and have a full 360 degrees of motion.
Their Beautiful Rainbow Color Isn’t bioluminescence
Comb jellies are famous for the stunning rainbow effect they display. Contrary to popular belief, this is not bioluminescence. The jellies are actually breaking up and refracting light, just like a prism would. This is important because they will not display this affect in the dark! To get the greatest refraction effect follow these guidelines:
Use a bright white light. White light is a combination of all the light colors. This will allow the jellies to create a true rainbow of colors.
Use a close source point. LEDs are a great example of this. You want a lot of light coming from a small source.
Add a dark background. This will really help the colors pop, and help you see the jellyfish better.
How to Care For Comb Jellies
The first thing to note here is that we sell Mnemiopsis Leidyi. This is one of the most common and definitely the hardiest species of Comb Jellies available. They are found in many places around the world, including the Atlantic. We collect and find these Comb Jellies in all seasons. They are incredibly versatile, and can exist in waters ranging from 55-78°F, and salinities of 1.020-1.026. With years of research, we have found the most optimal conditions to keep your comb jelly healthy and living the longest.
Keep your jellies in stable aquariums with no ammonia. Many jellies are tolerant of ammonia, but Comb Jellies cannot stand it. Only add Combs to tanks that are well cycled. Additionally, pH swings can be very damaging to Combs. Monitor the pH often.
Keep them cold. When kept at a temperature of 60-65°F your Comb Jellies will have much slower metabolisms, and their life span will be extended significantly. Additionally, the cold water will limit harmful bacterial growth.
Feed them a varied diet occasionally. It’s best to feed your Combs freshly hatched baby brine shrimp on a daily basis. Switch it up every now and then with frozen rotifers and live copepods. They will appreciate the snack!
Literature used to suggest Mnemiopsis Comb Jellies would only live two months. Using the three methods above, we have managed to keep our Comb jellies for well over a year in captivity.
Care Requirements Summed Up
Temperature: 55-78°F, Optimally 60°F
Ammonia: 0 ppm
Best Jellyfish Tanks: Orbit 20, Pulse 80, these jellies stay around 2″ long, Orbit & Pulse have ports for a mini chiller. Set flow to very low.
Diet: Will need live baby brine shrimp as main staple. Frozen/ live rotifers and live copepods are good options as well.
Other Species of Comb Jellies
Lastly, there are a few other species of Comb Jellies. They may have special requirements, or are difficult to get ahold of.
Sea Gooseberries: These Comb jellies are a small, round creature, with two long net-like tentacles. They are straightforward and easy to care for, but require a chiller, as they are a coldwater only species.
Beroe Comb Jellies: These are very bizarre jellies, and seem to poses a mouth. This “mouth” allows them to swallow other Comb Jellies (like mnemiopsis) whole. Their diet actually consists only of other Comb Jellies, making them very difficult to feed. They are also extremely delicate and only the most expert jellyfish aquarists should attempt these.
You can buy your own pet Comb Jellyfish and jellyfish aquarium at our online store: Jellyfish Warehouse
Okay so your jellyfish has suddenly turned inside out. Or maybe it arrived that way. Don’t panic, we can help!
When jellyfish turn inside out they are referred to as inverted, or sometimes everted. This problematic condition is somewhat common. Let’s take a look at what causes it, and what we can do to fix it.
Jellyfish are made of 95-97% water, and the rest is mostly protein. When protein is exposed to extreme or unfavorable conditions, such as heat, they change shape in a process known as denaturing. Think about how frying an egg makes it go from liquid to rubbery. Unfortunately, this very same process happens to jellyfish. The number one cause of inverted jellyfish is too much heat. Every species of jellyfish has an ideal temperature range, and when they slip past it, into the hot end, they risk winding up inverted. Always check your jellyfishes ideal temperature range before purchasing, and make sure your aquarium is at the correct temperature. Some other causes of inversion include: sudden change in salinity (usually too high), pH swings, and ammonia build up. Note that the key element here is speed. Change that happens too quickly can be very bad for your jellyfish.
Jellyfish that are inverted struggle with necessary processes, such as eating. Even if it looks like they are catching food, they are probably not able to disperse the nutrition around the body. A very small percentage of inverted jellyfish will return to their proper shape on their own.
So how do we fix this? Over the years we have come up with a couple of good methods for fixing your inverted jellyfish. Please proceed with caution, and understand that manually handling your jellyfish can help it, or make its condition worse.
Changing the salinity: We recommend trying this method first to see if it helps any. This is still based on anecdotal evidence, but it seems to have worked for many jellyfish keepers, including us. You want to bring the salinity up towards the high end of their comfortable salinity range. Before you ask, I know we just said above that high salinity can cause inversion. The idea here is to slowly raise the salinity, and keep it within their acceptable range. If they flip back to normal, you can slowly drop the salinity back to its original level. To change the salinity, we recommend preforming a water change with extra salty water. This will help bring the salinity up gently.
So maybe method #1 hasn’t done anything after a day or two. You may try manually flipping your jellyfish back to normal. Our favorite method of doing this goes as follows: Take your jellyfish * and put two fingers underneath it, right in the center. Begin moving the jellyfish slowly up to the water’s surface. Gently bring the jellyfish just up out of the water, but not all the way. The jelly should collapse back on itself, flipping into the correct shape. Understand
that this process can be risky for the jellyfish. Only attempt it if other options have not worked, and you feel skilled enough to properly handle it.
Once your jellyfish has been flipped back, it may invert again. This is fairly normal, and some jellies can be very stubborn. You can try flipping it back again, but we have found that these jellies will actually return to their normal shape, once you have manually flipped them a few times. So even if your jellyfish inverts again 30 minutes after you manually flipped it, don’t worry too much.
Jellyfish that have been inverted once in their life tend to be susceptible to inverting again in the future. Just make sure their water quality is good, stable and at the right levels.
*Please wear gloves or other protection when handling jellyfish that sting.
You can buy your own pet jellyfish and jellyfish aquarium at our online store: Jellyfish Warehouse
Atlantic Sea Nettles are a beautiful and stunning animal. They can be found in many different colors and patterns. Despite their delicate looks, these jellyfish make an excellent beginner jellyfish for the home aquarium.
They originate from the murky and brackish rivers and sounds of North Carolina and Virginia. Because they find home in rivers, they have strong, but smooth movements in the aquarium. Atlantic Sea Nettles are very different from their other Sea Nettle cousins. For starters, their size is much smaller, reaching a maximum diameter of around 5″. In captivity, this is usually 2-3″. Their tentacles are quite long, and typically measure 6″-1.5 feet. As you will find out below, their temperature, dietary and salinity requirements are quite different as well.
What do they eat? Atlantic Sea Nettles eat a wide variety of foods. They will happily consume our JellyFuel Dry Jellyfish food, and this makes an excellent staple for them. They will also gladly accept Mysis shrimp as a snack. Most Sea Nettles are “medusavorous” meaning they need to eat other jellyfish to survive. Atlantic Sea Nettles do not require this, meaning they do quite fine on our dry food alone. That being said, they will eat up any other jellyfish placed in their tank. It’s best that they be kept with other members of their species!
What parameters should the water be? Atlantic Sea Nettles should be kept at a salinity of 1.015 – 1.020 (21-27 ppt). Your eyes aren’t mistaken, they really should be kept at such a low salinity! They will do fine at higher or standard salinities, but we recommend keeping them at lower levels. We have yet to find any solid scientific evidence to support this, but it seems that salinity affects the colors and patterns of Atlantic Sea Nettles. In our experience here at the Jellyfish Warehouse Lab, we have found that salinities around 1.020 and higher cause the jellyfish to develop and all white color. Salinities more towards 1.015 may cause the jellyfish to develop stripes, spots, and blotches in red- dark burgundy. A lot of this is also based on genetics, so your sea nettle may still end up white, even if it’s at a lower salinity. Something to keep in mind if you purchase a young Atlantic Sea Nettle from us!
Atlantic Sea Nettles do great at room temperature, and can be kept all the way up to 77 degrees F (68-77°F). These jellies do well in tanks with decently strong flow, as they are stronger swimmers. They also do well in tanks with less flow, for the same reason. You will likely notice your Sea Nettles swimming against the flow. This is quite normal, as the fight the current and tides in their natural habitat. We recommend they be kept in an Orbit 20, Pulse 80, Pulse 160, Eon 2ube or 3on tank. They should be kept only with other Atlantic Sea Nettles, and stocked fairly low. Densely stocked tanks will end up with sea nettles tangling their tentacles together.
Do they sting?
Atlantic Sea Nettles do have a noticeable sting to them. They typically will cause a tingling sensation, like pins and needles, as well as an itching sensation. This usually subsides in a couple of minutes. Captive bred Atlantic Sea Nettles have a lesser sting, but we still recommend exercising caution when handling these jellyfish.
You can buy your own pet Atlantic Sea Nettle jellyfish and jellyfish aquarium at our online store: Jellyfish Warehouse
A popular jellyfish we offer are Mangrove Box Jellyfish. These odd little jellies are both entertaining and mysterious. They originally come from the Caribbean and surrounding areas.
Mangrove Box Jellyfish only get about 1″ in bell length and 2-3″ total length. This makes them perfect for small home jellyfish aquariums. They rapidly dart around the aquarium, making them instantly captivating.
What do they eat? In the wild, Mangrove Box Jellyfish eat live copepods, or plankton. When we first collected these jellies, this was an issue. They didn’t like to eat anything but wild plankton. We were able to selectively breed these jellyfish to produce a line that readily accept live Baby Brine shrimp. This may be easy enough for some and too much of a hassle for others.
What parameters should the water be? Mangrove Box Jellyfish should be kept at a salinity of 1.020 – 1.024 (27-32ppm) and a temperature of 77-80 F. These jellies prefer fairly strong flow, but seem to enjoy a variety of aquariums. We recommend they be kept in a Cnidarium Nano or an Orbit 20. Fairly tolerant of less than perfect water quality and conditions, these make a good beginner jellyfish. They should be housed with other Mangrove Box Jellyfish only.
Do they sting? Box Jelly immediately makes people think of the lethal Australian Box Jellies. Luckily, Mangrove Box Jellyfish are an entirely different story. They have a small, non lethal sting. Some report no feeling at all, whereas others report minor irritation or stings. As usual, we recommend you exercise caution when handling these jellies. If you know you have sensitive skin, you may be more prone to jellyfish stings.
You can buy your own pet Mangrove Box Jellyfish and jellyfish aquarium at our online store: Jellyfish Warehouse