In the marine aquarium hobby, there are two main types of marine parasites that are sometimes seen to affect our fish. They are Marine Velvet and Marine ich. This article deals specifically with marine velvet. Parasites are a natural occurrence in the wild and mother nature has provided a myriad of ways for fish to overcome them.
There are fish and crustaceans that perform cleaning services for affected organisms while the open ocean provides enough space for fish to escape the clutches of parasites altogether. Such is not the case in a closed system like our beloved marine aquariums. In our tanks, Marine velvet is absolutely lethal.
What is Marine velvet? Marine velvet is a parasitic dinoflagellate that also has photosynthetic capabilities – a deadly combination to be sure. Dinoflagellates are microscopic creatures that make up part of the planktonic soup in our oceans. Most of them are photosynthetic while others a parasitic in nature. The "Red Tide" that can sometimes occur off some coastal beaches are a result of a dinoflagellate bloom. The scientific name of the specific dinoflagellate we are dealing with is Amylodinium Ocellatum.
Considered to be far deadlier and more difficult to eradicate than marine ich, Amyloodinium Ocellatum does however have very similar breeding cycles with ich. While Marine ich can be seen with the naked eye, marine velvet is smaller (sugar sized) and needs careful inspection to detect it. As sugar sized spots on the fish, they feed off the tissues of the fish until they drop off to breed.
Once they are released into the water column, they require fish to survive. This cycle is almost exactly like that of marine ich with one big difference. While ich must find prey within 24 hours to survive, marine velvet can live up to two weeks before finally dying. This is because because they are photosynthetic and can survive for quite a bit with a light source.