We get this question quite frequently, and there is a lot of misinformation floating around the web. It’s understandable to be concerned when you buy a Moon Jellyfish for a desktop sized aquarium and then find out they can reach up to 15″ in diameter. Do not fear, science is here!
In short, your jellyfish will not outgrow your aquarium, and here’s why:
Jellyfish have two natural adaptations that make them excellent candidates for home aquariums.
- Jellyfish grow to fit their environment. Jellyfish are able to grow until they reach a happy and comfortable size in an aquarium. Once they reach this point, they either stop growing or slow down massively. This is why we offer different sizes of jellyfish. You can buy a small jellyfish, for your smaller sized tank.
- They alter their size based on how much food they have. In nature, jellyfish essentially bump into their food. A lot of their movement is based on tides and flow. So food isn’t always available to them. They have a clever adaptation which allows them to grow or shrink depending on how much food is available. Rather than starve to death, they decrease in size. So as a jellyfish owner, you can help moderate there size by controlling how much food you give your jellyfish.
Don’t just take it from us, worldwide jellyfish expert Dr. Lisa Gershwin says “If they start growing too big, just don’t feed them for awhile until they are back down to a convenient size, then start feeding again. It’s not cruel, it’s how they work. It’s called degrowth and regrowth, and it doesn’t hurt them.”
As you can see above, some jellyfish can get quite large. But when bred in captivity, the jellies can be purchased a smaller size, and kept that way. Just like your very own bonsai jellyfish!
You can buy your own pet jellyfish and jellyfish aquarium at our online store: Jellyfish Warehouse
Picture credits to
jellyfishwarehouse 
