Upside-down Jellyfish (Cassiopea) care guide
Cassiopea andromeda / C. xamachana · Cassiopeidae
Upside-down Jellyfish (Cassiopea andromeda / C. xamachana) is an aquarium animal. It belongs to the Cassiopeidae family. It is native to Shallow, sheltered, warm water: mangroves, lagoons, sand and mud flats, seagrass beds. C. andromeda is from the Red Sea and Indo-Pacific; C. xamachana from Florida and the Caribbean.. Water temperature: 22°C – 28°C. pH: 8.0 – 8.4. Care difficulty: Moderate.
How do you care for Upside-down Jellyfish (Cassiopea)?
| Light | High light: it hosts zooxanthellae, so use coral or clam-grade lighting (a retailer figure is about 200 PAR or more), 10-14 h a day, with blue and daylight spectrum. |
|---|---|
| Temperature | 22°C – 28°C |
| pH | 8.0 – 8.4 |
| Placement | Wide, shallow marine tank with a 2-5 cm fine sand bed; footprint matters more than depth; about 38 L (10 US gal) per animal. Not a kreisel, as it rests on the bottom. Salinity roughly 30-35 ppt. Keep intakes high and sponge-covered. |
| Growth | Bell reaches about 30 cm in the wild (commonly 20-30 cm); tank animals are often smaller. Growth is moderate. Lifespan is not well established: about 1 year by one source, several years with good care by another. |
| Difficulty | Moderate (retailers often label it difficult or expert; suits reef keepers with strong lighting) |
| Family | Cassiopeidae |
How do you trim and propagate Upside-down Jellyfish (Cassiopea)?
Do partial water changes to keep nitrate low, test for copper and replace lamps on schedule, since ageing lights starve the symbionts. Watch the pulse: slow or irregular means poor water or low light. Target-feed baby brine shrimp, rotifers or copepods a few times a week. Breeding is sexual; polyps bud and strobilate (monodisc, few ephyrae at a time), reported to start above about 20°C.
What problems affect Upside-down Jellyfish (Cassiopea)?
Pale, brown-washed or shrinking bell: too little light, lost symbionts or too little supplemental food. Tumbling or floating: flow too strong, air under the bell or a salinity change. Decline after medication or tap-water top-up: copper or other metals. Trapped on an intake: benthic jellies drift into screens.
How do you fix Upside-down Jellyfish (Cassiopea) problems?
Raise light to coral grade with a blue channel, run 10-14 h and add target feedings. Reduce flow, remove bubble sources and keep salinity stable. Never dose copper; use RO/DI water and test copper. Use wide screens and keep intakes high.
Where does Upside-down Jellyfish (Cassiopea) come from?
Shallow, sheltered, warm water: mangroves, lagoons, sand and mud flats, seagrass beds. C. andromeda is from the Red Sea and Indo-Pacific; C. xamachana from Florida and the Caribbean.
What should you know before buying Upside-down Jellyfish (Cassiopea)?
Sting is mild to variable: welts, rash, itching, and nausea or pain in sensitive people. Cassiopea also release stinging mucus particles (cassiosomes) into the water that can irritate skin without touching the animal. Wash hands after maintenance; keep allergic people away. C. andromeda is an alien species in Hawaii, the Mediterranean and Brazil: never release jellies, polyps or tank water. Unsuitable for tanks without strong lighting or with copper medications.
Sources
- Jellyfish (Cnidaria & Ctenophora) Care Manual, 3rd ed. (chapters 1, 5, 6; Mastigias entry as zooxanthellate reference) — Association of Zoos and Aquariums (AZA)
- Cassiopea — Wikipedia
- Cassiopea andromeda — Wikipedia
- Upside-down jellyfish (Cassiopea andromeda) — Reeflings
- Turn your tank upside down — Quality Marine
- Upside Down Jellyfish (product care data) — Quality Marine
- Snapshot of the distribution and biology of alien jellyfish Cassiopea andromeda in a Mediterranean touristic harbour — Biology (MDPI) via PubMed Central
- Cassiopea andromeda - Guidebook of Introduced Marine Species in Hawaii — Bishop Museum
- Upside-down jellyfish fact sheet — AQWA (Aquarium of Western Australia)
- Cassiopea xamachana (upside-down jellyfish) — Animal Diversity Web, University of Michigan
Care details checked against these sources on 2026-10-07.
See Upside-down Jellyfish (Cassiopea) in a living world
- Upside-down Jelly Lagoon — aquarium
Last updated · Open the interactive 3D guide · All species care guides