Fried Egg Jellyfish
Cotylorhiza tuberculata
A whimsical species of jellyfish that truly does resemble a fried egg, sunny side up! Found exclusively in the Mediterranean Sea, usually in late summer. Younger specimens have a more flattened bell with a light yellow color. Older specimens will have a definitive sunny side up shape and the central bump in their bell turns an orange reddish color.
Caring for Fried Egg Jellyfish
Fried Egg Jellies are a fairly hardy and resilient species with just a few special requirements. Although tolerant of a fairly wide range of parameters, they have a few preferences which we cover below.
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Stocking density: Lacking tentacles, Fried Egg jellies can be kept pretty close together.
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Flow: Medium is ideal with this species. They are moderately capable of keeping themselves suspended so they only need a little water movement to help. That being said, they are relatively tolerant of higher flow. Juveniles under 2" diameter sometimes like to suction cup to the side walls of the aquarium. Upping the flow can help keep them off the walls until they outgrow this phase.
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Feeding: Live baby brine shrimp are ideal, live or frozen rotifers can also be incorporated.
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Temperature Range: 75-82 F
Salinity: The Mediterranean often sits at a slightly elevated salinity. Because of this, Fried Egg Jellies are tolerant of, and may benefit from a higher salinity as well.
1.026 SG or 35 ppt
Life Stages
Each golden dot is a cell of symbiotic algae living within the jellyfish
Polyps: Resemble wineglasses with triangular heads and long stalks. Stalks are typically thicker and shorter than Cassiopea, Phyllorhiza and Mastigias. More closely resemble Netrostoma or Cephea. Asexually reproduce by releasing ciliated planuloid buds which swim away and settle into new polyps. No podocyst formation. Monodisc strobilation.
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Ephyra: Clearish and typically dotted with golden symbionts.
Common Diseases and Troubleshooting
Suction Cupping: Younger fried egg jellies are suction cup shaped and this often leads to issues with them sticking to the sides of the aquarium. A carefully dialed in flow will help prevent this. Some public aquariums have also prevented this by lining the inside of the tank in bubble wrap. I personally like to add a few rigid airline tubes near the problem areas and set the bubble rate to 1-2 per second. This helps push the jellies away. Ultimately, jellies that have successfully grown past 1"-1.5" diameter stop having this issue because they develop the characteristic "egg yolk" bump in the center of their bell.