Species group: Jellyfish
Other common names: Blue Jellyfish, Blubber Jellyfish
Scientific name: Catostylus mosaicus
With its “other-worldly” appearance, the Blue Blubber Jellyfish is becoming very popular in public aquariums. Serious specialists have been able to maintain it at home, but large tanks designed specifically for pelagic species are required for success.
The Blue Blubber Jellyfish ranges from the shores of Southeast Asia to Australia. It is an open-water species, often travelling in swarms large enough to clog commercial fishing nets (perhaps an example of “natural eco-activism”?!).
Appearance / health:
The body is translucent, and takes on a unique appearance and color tone depending upon the type of light under which it is viewed. Adults reach 30-46 cm. (12-18 in) in diameter, and are beautifully-colored in varying shades of blue, purple, white, yellow or red.
The Blue Blubber Jellyfish may live to age 12 months with proper care, but is a delicate captive. Insufficient lighting, starvation, and poor aquarium design (see below) are the most common causes of fatalities. Jellyfishes cannot tolerate copper-based medications, ammonia, or nitrites.
Behavior / temperament:
The Blue Blubber Jellyfish remains continually in motion and, in the wild feeds throughout the day and night. Its sting is considered mild, but induces an itchy irritation; the possibility of individual sensitivities or allergic reactions must also be considered. Jellyfishes are best housed with others of their kind, as their stings can injure or kill various invertebrates and fishes.
Blue Blubber Jellyfish should be kept in a Kriesel, which is a circular aquarium specifically designed for jellyfish. Kriesels are equipped with a filtration and pump system that creates the type of current flow that is essential for keeping jellyfish in motion and feeding in the water column. The tank is bare, as jellyfish easily become entangled in coral and other structures. Blue Blubber Jellyfish require powerful lighting, so that the symbiotic zooxanthellae (single-celled protozoans), which provide the jellyfish with nutrients, can thrive.
The following water quality parameters are critical to long-term health:
Specific Gravity (Salinity): 1.023-1.025; Temperature: 24-26 C (75-78 F); pH: 8.1-8.4; Alkalinity 8-12 dKH; Ammonia/Nitrites: 0; Nitrates: below 5 mg/l. Calcium, iodine and other trace elements should be added as suggested by the product manufacturer.
In addition to the nutrients produced by the photosynthetic zooxanthellae, Blue Blubber Jellyfish should be provided large daily feedings of newly-hatched brine shrimp and, if available, zooplankton. Brine shrimp should be nutritionally enriched with a commercial algae-based diet designed for that purpose (i.e. Selco) beforehand. Blue Blubber Jellyfish may also derive some benefit from plankton formulas designed for use with filter-feeding marine invertebrates, and sometimes accept finely-chopped frozen krill.
Blue Blubber Jellyfish reproduce sexually and asexually, going through several stages that differ greatly in appearance and lifestyle before becoming an adult, or medusa. Survival of the larval stages seems to depend upon a ready availability of plankton-based foods.
Written by Frank Indiviglio