Care for Moon Jellies
Temperature preferences: Tropical-temperate-coldwater
True jellyfish- yes
Food preferences- Moon jellyfish can live in captivity with a main diet of baby brine shrimp (Artemia nauplii). Live food is best, but they can eat high quality frozen or preserved baby brine shrimp. Cyclopeze or other red copepods are harmful towards their health and will cause the jellyfish to decline in size. Moon jellyfish can also eat regular live copepods, blended krill and shrimps, rotifers, amphipods some very fine powder foods. Large adult moon jellies can also be fed small krill.
Tank preferences: Moon jellies will do okay in almost anything with proper flow. They need to stay totally suspended in the water. Some sort of flow is necessary for them to do this. I have kept moon jellies in cylinder tanks, pseudokreisels, and flow through style breeding systems. They should also do well in tumbler tanks, kreisels, stretch kreisels, modified tanks etc.
Life cycle: Embryo-planula-polyp-strobila-ephyra-metaphyra-juvenile-adult
Life span-About 1 year.
Description: Moon jellyfish are a fairly clear jellyfish. They are round and semi flat. Four oral arms exist in the center and thousands of hair like fringe tentacles exist at the edge of their bells. They have four gonads and stomach in the center of their bells. Moon jellyfish are fairly easy to keep and common. They also breed well. Because of these factors, they are the most commonly kept jellyfish. They were also my first jellyfish. I would say that they are the easiest jellyfish to keep that swims actively and looks fairly impressive.
Breeding: Breeding Moon jellyfish isn't particularly difficult. It can be challenging at first, but it becomes routine with practice.
Planula: Planula are fairly tiny and arent particularly visible to the naked eye. Moon jellyfish also brood planula on their tentacles before they are released.
Polyps: Polyps of moon jellyfish are fairly small. Some species bear smaller polyps than others. Polyps grow near by one another in nature and in captivity. Moon jellyfish polyps tend to reproduce and clone very fast. Large colonies can be formed in reasonable distances of time. These polyps seem to prefer to be left alone, where as some jellyfish polyps like to have a well cleaned surface to grow on. Polyps can be reared in dishes and containers with standing water for long periods of time. The healthiest polyps are ones in tanks of flowing water, with the containers flipped upside down so the polyps hang.
Strobila: The strobila often form on their own every few months. Some warm water polyp colonies will produce strobila weekly. In my personal experience, the faster polyps created ephyra that were a lot harder to raise than the ones that were slower. Colder water moon polyps will produce strobila at a slower rate at about once a month or even once or twice a year. It is fairly common to see anywhere from 12-24 ephyra per strobila. Less than that could be a sign of low health. Strobila of warm water polyps that are placed in colder climates will begin to fall apart.
Ephyra and Metaphyra: Ephyra can be raised in 8” dishes of saltwater (changed daily) or raised in flow through breeding systems. I find that the species of warm water moon jellyfish that produces ephyra weekly prefer a very clean environment. In this instance, keeping them in low batches in dishes will be suitable. In most other cases, large batch flow-through systems seem to be optimal. Ephyra can be raised entirely off of baby brine shrimp. Rotifers can also be used as a food source. This will keep the tanks cleaner.
Juveniles and Adults: Juveniles should be moved to larger tanks. It is best to move them once they have the beginnings of 4 oral arms. You may be able to also see some fringe tentacles. Adults should also be put in tanks that are appropriate for their size. Moon jellyfish tend to grow and fit their environments well. Left in a large enough tank and they can reach a max size of 12-14 inches across the bell.