Add one of the ocean’s most unusual inhabitants to your marine aquarium with the Upside-Down Jellyfish. Unlike free-swimming jellyfish, Cassiopea sp. naturally rests bell-down on the substrate with its branching oral arms extended upward toward the light.

Its unusual appearance and gentle pulsing movement create a living display resembling a small underwater flower. Symbiotic algae within its tissues provide part of its nutritional needs through photosynthesis, making proper lighting and an open sand bed essential to its care.

Care Requirements

• Care level: Intermediate to expert
• Temperament: Peaceful
• Reef compatible: No
• Maximum size: Approximately 5–8 inches
• Recommended aquarium size: 30 gallons or larger
• Temperature: 72–78°F
• Specific gravity: 1.023–1.025
• pH: 8.1–8.4
• Alkalinity: 8–12 dKH
• Water movement: Low and gentle
• Lighting: Moderate to high reef-spectrum lighting
• Diet: Carnivore and filter feeder

Recommended Aquarium

Upside-Down Jellyfish do not require a kreisel aquarium. A conventional rectangular, breeder, or shallow lagoon-style aquarium is preferred because bottom area is more important than aquarium height.

A 30-gallon breeder or larger shallow aquarium is recommended for a pair. Larger aquariums provide more usable sand-bed space, greater water stability, and additional room as the jellyfish mature.

Tank Requirements

• Wide and shallow aquarium with ample bottom area
• Open sand bed with 1–2 inches of soft, fine aquarium sand
• Minimal rockwork and no sharp decorations
• Gentle filtration using a sponge filter or carefully baffled return
• No exposed pump, powerhead, overflow, or filtration intakes
• Intake guards or fine protective foam over all accessible openings
• Moderate to high reef-spectrum lighting positioned above the sand bed
• Stable, fully cycled saltwater aquarium
• Low nitrate levels and absolutely no copper-based treatments

Avoid strong water movement. Excessive flow can prevent the jellyfish from settling, repeatedly overturn it, or push it against aquarium equipment.

Lighting

Upside-Down Jellyfish contain symbiotic photosynthetic algae and require consistent reef-spectrum lighting. A light suitable for photosynthetic corals is recommended. The aquarium’s shallow design helps deliver sufficient light to the jellyfish resting on the sand bed.

Feeding

Photosynthesis provides only part of the animal’s nutritional needs. Regular supplemental feeding is still required. Offer appropriately sized foods such as enriched baby brine shrimp, copepods, rotifers, zooplankton substitutes, or other fine marine foods.

Feed small portions near the jellyfish and remove uneaten food to protect water quality.

Tankmates

A dedicated species aquarium is strongly recommended. Upside-Down Jellyfish can release mucus containing stinging cells into the water, potentially irritating fish, corals, and other aquarium inhabitants.

Do not house them with animals that may bite, pick at, sting, bury, or otherwise disturb them.

Important Information

The Upside-Down Jellyfish is not suitable for a kreisel aquarium designed for free-swimming jellyfish. It requires an open sand bed, strong lighting, gentle flow, and sufficient bottom area.

Use care when handling the jellyfish or performing aquarium maintenance because its stinging cells may cause skin irritation. Sudden changes in temperature, salinity, or pH should be avoided.

Live Animal Shipping

Live fish, corals, and invertebrates are shipped Monday through Wednesday via FedEx Priority Overnight. A $39.99 overnight shipping fee applies per live-animal order. Qualifying live-animal orders of $300 or more receive free shipping.

Each specimen is unique. Color, size, and appearance may vary from the representative image.