Blue Blubber Jellyfish

About

The blue blubber jellyfish (Catostylus mosaicus) is one of the most recognizable jellies along the Australian coastline, where it appears in enormous aggregations in estuaries and coastal bays. Unlike many jellyfish, its coloration is variable. Individuals range from white or cream through to deep blue, brown, or even purple, with a smooth, dome-shaped bell that lacks the trailing tentacles most people picture on a jellyfish. Instead, it feeds through eight fleshy oral arms hanging beneath the bell, which capture plankton and small organic particles. In the aquarium, the absolute requirement is a kreisel tank. A purpose-built, circular flow vessel that keeps the animal gently suspended in the water column without getting it sucked into a filter or damaged against a flat wall. This is not a community tank inhabitant by any stretch; it cannot be kept with fish or most other invertebrates. Feeding is done with live or frozen copepods, rotifers, and similar tiny food items introduced directly into the water flow. Care is genuinely intermediate. The husbandry challenges are more about equipment and water quality consistency than aggression or diet complexity. Lifespan is short, typically around a year, so many keepers source new animals regularly.