About White Spot

Introduction of Oodinium and Ich.

The most common diseases that affect marine aquarium fish are caused by Amyloodinium and Cryptocaryon. These diseases are widespread and can cause serious illness and death in aquarium fish if not recognized and treated quickly and properly. Amyloodinium and Cryptocaryon are extremely hardy and can withstand a wide variety of salinity and temperature fluctuations. They can infect any fish at any time, but they appear to be much more of a problem when new fish are brought into an aquarium.  As with almost all parasitic infections, most fish can fight off minor infections providing their immune system is strong. Most new fish caught from the wild are stressful in aquarium tanks and their immune systems are not able to fight off minor infections.

Life cycle of Amyloodinium

The life cycle of Amyloodinium is very similar to Cryptocaryon and is composed of multiple stages. The free-swimming organism is called a dinospore. When it attaches to the fish's skin, it is called a trophont. The trophont feeds on the fish for several days and then detaches. Once detached, it is called a tomont. The tomont divides and produces between 64 and 256 motile infective dinospores that attach to the fish and become trophonts starting the life cycle all over again.

(A).Trophont on skin of fish

(B)Trophont detaches and becomes a tomont

(C).Tomont divides

(D).Tomont releases dinospores that will attach to the fish


Diagnosis is usually made based upon history and symptoms, but scrapings of the skin or white spots on the skin can be performed and the trophonts identified. Other symptoms usually include twitching, flashing, and other signs of stress and irritation. Another technique is to place the infected fish in fresh water for several minutes and the organisms will drop off. The surface water can be poured off and the sediment can be examined microscopically.


Fenner, R.M. The Conscientious Marine Aquarist. TFH Publications. Neptune City, NJ; 2001. Noga, E.J. Fish Disease Diagnosis and Treatment. Iowa State University Press; 2000. Stoskopf, M.K. Fish Medicine. W.B. Saunders Co. Philadelphia, PA; 1993. Tullock, J.H. Natural Reef Aquariums. TFH Publications. Neptune City, NJ; 2001.