Parasites: White Spot

For those who own or have owned an aquarium, Ichthyophthirius Multifiliis, or White Spot, is likely a familiar phenomenon. This parasite occurs on many fish species. White Spot belongs to the group of protozoa and is a ciliate ( parasites in general ). A ciliate is a round to oval-shaped protozoan with cilia all around for locomotion.

White Spot is one of the few protozoa that can be diagnosed with the naked eye. The protozoa itself is not visible to the naked eye, but its effects are highly specific. The protozoa causes white, efflorescent growths on the skin of the fish, up to one millimeter in size, giving it its Dutch name. These "salt grains" are particularly visible against a dark background. However, it is wise to determine whether it is truly White Spot through microscopic examination. Because the parasite is quite large in the protozoan world, it is easily identified at 100x magnification. Under a microscope, White Spot appears as a slowly moving, round, brown to black sphere (not to be confused with an air bubble, which also appears as a black sphere under a microscope). Adults have a horseshoe-shaped, lighter core.

White spot reproduction is complicated. Adults form cysts that fall off the fish. Within these cysts, the white spot multiplies into several hundred individuals, which, after bursting, search for a new host. Upon finding one, they encapsulate themselves and feed on the fish's skin cells, reaching adulthood, after which the cycle repeats. This strategy allows for rapid spread, which is why Ichthyophthirius Multifiliis is called "plague with many sons."

A White Spot outbreak in a pond can cause a real devastation. In addition to treatment, it's important to identify and eliminate the cause. This is usually a weakened fish due to poor water quality, temperature fluctuations, and/or stress. If you don't address the cause, you'll soon be faced with the next parasite outbreak. Reinfection due to the introduction of infected fish is also a common cause. Therefore, always test new fish for parasites, or better yet, introduce them to a new environment first. quarantine .

Always follow the product's instructions carefully when treating the cysts. The cysts are resistant to most medications, so long-term treatment (depending on the water temperature) or multiple treatments are necessary to break the cycle. Short-circuit your filter, otherwise the bacteria in the filter will be destroyed, and you'll be in even worse shape. Given the duration of the treatment, you don't need to worry about re-infection from surviving white spots in the filter; they will die because they can't find a host. Treatments for white spots are usually such as: FMC used.

Author: Joop van Tol (www.koitoday.nl)