INTERMEDIATE SIZED SYSTEMS — 125 TO 250-LITRES

SEA JELLIES

6Scientific name: Examples include the Moon jellies, Aurelia sp., and Blue cannonball jellies,

Stomolophus meleagris

6Distribution: Circumtropical (many temperate species occur)

6Price Range: £15-70

6System Size: Dedicated sea jelly aquaria come in a variety of sizes from only 30-litres or so upwards. Water quality can be difficult to maintain in such small volumes so choose carefully.

Larger may be better for you and the animals concerned.

While some of the species available be housed in a typical box aquarium, planktonic sea jellies need something designed to keep them in the water column. Often, a ‘kreisel’ system is employed (from the German word for a spinning top or roundabout, in acknowledgement of their circular shape) which create water currents that provide uplift to the animals inside, while simultaneously keeping them away from the edges of the tank where they may tear themselves.

Sea jellies are weak swimmers and cannot handle the vigorous currents found in standard reef aquaria. They get pulled against wave pumps or flop over weirs and should not be attempted in anything other than aquaria designed to meet their exacting requirements.

Sea jelly systems were once the reserve of large public aquaria but it is possible to purchase dedicated aquaria relatively cheaply with rounded corners, in oval or circular shapes (all variations of the original kreisel design) that enable water currents to keep the jellies suspended in the water column. A well-run jelly aquarium makes for a wonderful display of some truly beautiful and engaging animals but the relatively small volumes of many entry level kreisel-style systems mean that aquarists need to be on their game with regard to maintenance and feeding if their livestock is to thrive.