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This comprehensive care guide will show you how to look after a Jellyfish in 3 easy steps


Fast Facts:

How long will my Jellyfish live? 1 year

How big will it grow? Up to 15cm in captivity

What size tank is recommended for my Jellyfish? A specially designed jellyfish aquarium

What does a Jellyfish eat? Brine shrimp, rotifers and mysis

Jellyfish Housing

Moon Jellyfish are the most commonly kept species of jellyfish and have easy husbandry requirements. They are especially popular because of the relaxing movements they make and their white opaque colouring.

Jellyfish can damage themselves in normal fish tanks so they require a specially designed jellyfish tank, which has curved edges and a weak water flow to avoid damaged the delicate skin of the jellyfish.

They can hold numerous Moon Jellyfish, however, the number that can be kept within the tank is dependent on the size of the jellyfish. Moon Jellyfish come in a variety of sizes, with the small juveniles being only 2-3cm in diameter and the larger adults reaching up to 15cm.

Jellyfish Care

The temperature of the tank should be around 18-25˚C, which in most situations is a couple of degrees below room temperature, negating the need for any heating. Water quality tests should be done every few days after first adding jellyfish to the tank to ensure levels are maintained within the recommended parameters, however once the tank is established water testing can be carried out weekly. pH should be kept between 7.9 and 8.4 and salinity at 34-35ppt (natural seawater).

A 10% water change should be undertaken weekly, however the frequency of water changes is dependent on how populated the aquarium is. Newly mixed salt water can be stressful to your jellyfish as it is quite unstable, so it is generally safer to purchase pre-prepared salt water refills.

The filter sponge should be removed and thoroughly rinsed under a tap on a monthly basis, and every 6 months the pump and filter should be fully cleaned. Over time, uneaten food and other waste can build up on the bottom of the tank, and algae may begin to grow on the side of the tank, especially if the tank sits in direct sunlight. This can be removed with a sponge and the debris can be siphoned out of the tank, but care should be taken to ensure no jellies are damaged in the process.

Due to their bell shape, Moon Jellyfish can occasionally become stuck against the walls or bottom of the aquarium, much like a suction cup. If you observe them like this move them away gently by wafting water across them.

You should avoid creating air bubbles as much as possible as they can get caught within the bell of the jellyfish. If this occurs you must gently turn them upside down and massage them to release the air.

Jellyfish Food

Moon Jellyfish can be fed live or frozen brine shrimp, rotifers or mysis. To feed your jellyfish prepare the correct amount of food in a cup and pour slowly over the surface of the water; this can be done bit by bit until the jellies stomachs are visibly full to avoid overfeeding and creating waste in the aquarium.

Any uneaten food should be removed after feeding as it can degrade the water quality within the aquarium if it is left.

Did You Know?

Moon Jellyfish are an opaque white colour, however, by putting them under different coloured LED lights in the aquarium they will appear to change colour! 


We have created a Shopping list to show what you need to look after a Jellyfish:

  • Specially designed jellyfish aquarium
  • Water siphon
  • Algae scrubber
  • Thermometer
  • Salt water
  • pH test kit
  • Ammonia test kit
  • Nitrite test kit
  • Hyrdometer
  • Refractometer
  • Net
  • Frozen brine shrimp
  • Live brine shrimp
  • Rotifers
  • Mysis
  • Feeding syringe

Common health issues in Jellyfish

Shrinking: When jellyfish are shrinking (or just not growing) it is generally due to poor water quality in the aquarium. Jellyfish will not feed properly while the water quality is low, so this can lead to them not growing properly. Overcrowding of the aquarium can also contribute to poor water quality.

Red flags

Is your Jellyfish showing any of the signs of disease or illness? If yes, please contact your vet.

  • Missing tentacles
  • Holes in their bell

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FACT SHEET © Copyright 2016 Kellyville Pets - The information in this brochure is meant as a guide only. Kellyville Pets take no responsibility of any description for any consequence and or result that may eventuate as a consequence of any information obtained from this brochure.