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We are frequently asked about how to successfully keep jellyfish as pets. This post provides a quick introduction to the essential equipment required to keep jellyfish.
Jellyfish offer a rare opportunity to bring the quiet elegance of the ocean into the home. With their translucent bells, rhythmic pulsing, and ethereal glow under soft lighting, they create a living display that is both calming and captivating. Unlike traditional aquarium animals, jellyfish require a specialised environment that rewards careful setup and attentive care with a truly unique experience—one that feels closer to curating a living art installation than keeping a conventional pet. For aquarists seeking something distinctive, serene, and visually striking, jellyfish represent an extraordinary blend of natural beauty, scientific fascination, and refined aquatic design.
Equipment
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Aquarium - Jellyfish require a kreisel style aquarium, which creates a circular, laminar flow current that keeps them gently suspended thus preventing them from getting stuck to surfaces, getting trapped in corners or stuck to filtration intakes. A rectangular aquarium won’t work because jellyfish will sink, get trapped in corners, or get damaged by filtration intakes. The TMC Kreisel Aquariums are the ideal jellyfish aquariums for beginners and expert jellyfish keepers, available in 10L and 15L models. These aquariums come complete with LED lighting and filtration in built.
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Salt Water - Jellyfish require carefully Prepared Saltwater to thrive, as maintaining the correct salinity is essential for their health. A marine salt mix must be combined with fresh water to achieve stable, ocean-like salinity for both the initial aquarium setup and all routine water changes, ensuring consistency and minimising stress. Because evaporation causes salt to remain behind while water is lost, only fresh Reverse Osmosis (R.O) water should be used for top-ups, never saltwater, to prevent salinity from gradually rising. Using R.O water also avoids harmful impurities such as chlorine, metals, and nutrients commonly found in tap water. Sturdy food-grade Jerrycans are strongly recommended for mixing, storing, and transporting from the store both saltwater and R.O water, allowing the preparation of water in advance and perform maintenance safely and efficiently without sudden changes to water chemistry.
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Refractometer - A Refractometer is an essential tool for accurately measuring and regularly checking the salinity of a jellyfish aquarium, as even small fluctuations can have serious effects on jellyfish health. Correct salinity supports proper osmotic balance, tissue integrity, and normal pulsing behaviour, while levels that are too high or too low can quickly cause stress, shrinking, or long-term damage. Because jellyfish are far more sensitive than most marine animals, routinely verifying salinity with a refractometer ensures a stable environment and helps prevent issues before they become harmful.
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Live Rock - Adding a small amount of Cured Live Rock Rubble to the filtration system of a jellyfish aquarium provides valuable biological filtration without placing the jellyfish at risk. Cured live rock hosts beneficial bacteria that help break down waste products such as ammonia and nitrite, improving overall water quality and stability. When kept out of the main display area—such as in a rear chamber or sump—it enhances the aquarium’s natural filtration while avoiding sharp surfaces or obstructions that could injure the jellyfish, making it a safe and effective way to support a healthy system.
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Food - Jellyfish require small, appropriately sized foods that they can easily capture as they drift through the water. Their diet typically consists of frozen or live Brine Shrimp Nauplii, which closely resemble the plankton they feed on in the wild and provide reliable nutrition when fed regularly. Ready-Made Dry Jellyfish Foods are also available and offer a convenient alternative, especially for daily feeding, though they may be used alongside brine shrimp for balanced nutrition. Providing the correct food in small, frequent feedings is essential to support healthy growth, strong pulsing, and overall vitality.
The equipment outlined above provides a solid foundation for anyone beginning their journey into jellyfish keeping, covering the essential tools needed to create a stable and safe environment for these delicate animals. With the right preparation and understanding, setting up a jellyfish aquarium can be both rewarding and enjoyable. Be sure to look out for our next post, where we’ll guide you step by step through the initial setup of your jellyfish aquarium and help you get started with confidence.