Can You Keep Jellyfish in Your Aquarium? Complete Guide

Jellyfish, fascinating marine invertebrates without brains, stomachs, or eyes, are closer relatives to plankton and corals than fish. Despite their delicate nature, it is entirely possible to keep jellyfish as pets if you can provide the right environment and care. This complete guide covers the essentials you need to know to start your jellyfish aquarium journey responsibly and successfully.

1. Choosing the Right Tank

Standard square or rectangular tanks are unsuitable for jellyfish because the sharp corners can trap them, causing injury or death. Instead, a cylindrical or kreisel-shaped tank is ideal to create a gentle, continuous water flow that mimics ocean currents and prevents the jellyfish from getting stuck or sucked into filtration equipment.

Specialised jellyfish aquariums are designed with smooth, rounded interiors, and careful placement of pumps and filters to protect their fragile, boneless bodies. Investing in or custom-building such a tank is crucial to a healthy jellyfish habitat.

2. Water Flow and Filtration

Jellyfish rely on currents to swim and survive, so setting up proper water flow is essential. The flow should keep them gently suspended and moving without stress or suction injuries.

Filters must be jellyfish-safe, avoiding strong suction or sharp mechanical parts. Biological filtration can be beneficial but must not remove food particles too quickly or create harmful bubbles. A surface skimmer can help maintain water quality, but traditional power filters are often unsuitable.

3. Selecting Suitable Jellyfish Species

A variety of jellyfish species exist worldwide, but not all adapt well to captivity. The Moon Jellyfish (Aurelia aurita) is among the best choices for first-time keepers. Native to temperate and tropical waters such as bays and harbours, they grow up to 30cm across and reproduce well in captivity under proper care.

4. Water Temperature Management

Unlike tropical fish, many jellyfish species require cool water temperatures ranging from 12 to 18°C (54 to 64°F). Maintaining this often means chilling the tank water, as this range is generally cooler than typical room temperature. This cooling helps simulate their natural environment and supports health and longevity.

5. Maintaining Water Quality

Marine water quality must be pristine for jellyfish. Keep ammonia and nitrite levels at zero, with proper salinity levels (typically 30-34 ppt) and stable pH.

High-grade filtration systems including mechanical filtration to remove solids, biological filtration for waste breakdown, and optionally protein skimmers (used cautiously) are recommended. Frequent water changes and monitoring are crucial to avoid stress and disease.

6. Feeding Your Jellyfish

Jellyfish are voracious eaters, consuming large quantities of plankton and baby brine shrimp in the wild. To meet their high demand, you can purchase live or frozen foods from marine aquarium suppliers or maintain your own cultures of plankton and brine shrimp.

Ensure regular feeding schedules — often daily — and monitor food intake carefully. Many first-time keepers underestimate the amount and frequency jellyfish require, which can lead to poor health or starvation.

7. Lighting Requirements

Bright, strong aquarium lighting promotes the growth of algae which is part of some jellyfish diets and helps mimic natural conditions.

Select quality lighting products and consult your aquatic specialist to fit lighting that supports jellyfish health and visible display, especially important for species that rely on photosynthetic symbionts.

8. Safety and Handling

Jellyfish stings can be painful and occasionally trigger allergic reactions. While Moon Jellyfish have mild stings, it’s best to avoid direct contact where possible.

Handle tank maintenance with care. Always wear disposable gloves when working inside the tank to avoid stings and protect yourself and the jellyfish.

Conclusion

Keeping jellyfish in an aquarium is a rewarding but specialised hobby. Success depends on creating a carefully controlled environment that replicates their natural habitat, including a specially designed tank, proper water flow, correct temperature and filtration, and attentive feeding and handling routines.

With dedication and proper equipment, you can enjoy the unique beauty of jellyfish in your home for years. Always research thoroughly and seek expert advice before starting, and ensure you source your jellyfish and supplies responsibly.