Pet Jellyfish Facts: Keeping Jellyfish in Captivity and the Home Aquarium Fish Tank

Fish keeping dates as far back as ancient Sumerian, 2,500 BC. The Romans, Greeks and Egyptians all kept fish as pet. The Greek philosopher Aristotle was the first person known to have studied fish (382-322 BC). He documented the characteristics of 115 different species living in the Aegean Sea. Roman ingenuity allowed for one of the marble walls of a fish tank to be replaced with a glass pane for better viewing in 50 AD. The Chinese began crossbreeding the Prussian carp to create the forerunner of the modern goldfish over 1,000 years ago. In 1369, Chinese Emperor, Hongwu, established the first porcelain company to manufacture porcelain tubs to keep goldfish in. The world’s first public aquarium opened in Regents Park, London in 1853. The number of fish kept as pets in the USAis only surpassed by that of cats. There are more fish in American homes than there are dogs. Yet the first jellyfish exhibit ever to be seen by the public opened in Monterey California only twenty years ago.

It is little coincidence that the World’s first jellyfish exhibit only opened two decades ago. Until shortly before then it was thought impossible to keep jellyfish alive in captivity. Jellyfish are one of the most fragile creatures in the entire aquatic kingdom. Water constitutes 95% of their body mass. Only a thin epithelial membrane stands between them and utter destruction. Even something as harmless as a standard aquarium filter can prove deadly. A jellyfish can be sucked into its intake and liquefied instantly.

The ground work for being able to keep jellyfish alive in cavity was first laid in 1969 by German marine biologist, Dr. Wolf Greve. Dr. Greve engineered a totally new concept in aquarium design to help in his efforts to study Arctic plankton aboard ship rather than in their natural habitat. The basic design concept was to sandwich a cylindrical cross-section between two sheets of acrylic. What was revolutionary was the way in which the water circulated inside the tank. Water enters and exits the aquarium through screens at the top of the tank. This sets the water spinning in a slow circular motion. The water circulation acts to keep the fragile life forms away from the sides of the tank and gently tumbles them toward the center. Dr. Grve named his invention the kreisel (German for carousel) because the delicate ctenophores were perpetually suspended in a merry-go-round type motion. Planktonkreisels have become standard equipment onboard oceanographic ships.

The Kreisel concept was instrumental in creating the first jellyfish exhibit at the Monterey Aquarium. In just a few short years jellyfish exhibits were popping up in public aquariums all over the world. It was only a matter of time before this technological advancement sparked the minds and ingenuity of adventurous entrepreneurs. The market was set in place among high-end saltwater aficionados as soon as public aquariums started featuring jellyfish exhibits. That created a ready made niche just waiting to be filled.