Tropical Fish Disease

White Spot Disease

Ichthyophthirius

In early stages there may be no visible spots, but fish may scrape themselves on solid objects. The typical "white spots" which appear are pin-head sized and occur initially on the tail and fins before spreading to other parts of the body.

Symptoms:

In advanced cases the fish may appear to have been sprinkled with sand, and secondary diseases such as fungus and slime diseases may occur, leading to a white film or cotton-wool like growths in addition to the small white specks. Velvet (Oodinium) has a similar appearance to white spot, but the spots are finer, sometimes not even visible to the naked eye. Less distinct or larger white spots are more likely to be caused by fungus, slime disease, columnaris or lymphocystis.

Ich is a tiny parasite with a complex life-cycle. The ich parasite produces cysts which can survive several weeks in the aquarium even without a suitable host fish being present. When these cysts rupture they release free-swimming parasites which infect the fish and cause the visible white spot stage. During this stage the parasite lives and grows within the epidermis of the fish. Once they have grown to a suitable size the parasites leave the fish and produce a cyst. Within the cyst they divide for about 20 hours until the cyst ruptures, releasing thousand more ich organisms which then re-infect the fish. If a fish dies, the ich parasite rapidly leaves the body and after a few days these free-swimming parasites mate to produce long-lived cysts once more.

Prevention:

Because the encysted stages of ich are highly resistant to medication, ich is difficult, if not impossible to prevent using prophylactic medication. The occurrence of ich will be minimised in aquariums where the temperature is very stable, since temperature fluctuations are one of the major fasctors promoting outbreaks of ich. If detected early, treatment is easy, but due to the nature of the ich lifecycle, medication should be carried out over a period of 10 days or more, not just until the visible signs of the disease have gone. Remember, even when there are no visible white spots on the fish, fee-swimming or encysted stages may be present in the aquarium.

Treatment:

Treatment is most easily achieved at warmer temperatures, since these speed up the ich life-cycle. Make sure the temperature is at least 26°C, 28 to 30°C is better if the fish can tolerate these temperatures. Medications containing a combination of formalin and malachite green are the most effective. Use these strictly according to directions, and reduce the dose for tetras, baby fish and scaleless fish such as loaches. For medications without formalin, treat the fish on days 1,2,3,5,7 and 10, for those with formalin, treat every 3 days for ten days (ie on days 1, 4, 7 & 10).

A small water change prior to treatment is beneficial, ideally, perform a small water change (10 to 20%) every few days while treating. Prompt treatment is essential. The ich parasite will rarely kill the fish, but since it damages the skin, the fish is then left open for secondary infections which may be far more detrimental. If ich is treated promptly, these secondary infections should be prevented. If secondary infections are present, treatment for these will usually need to be carried out as soon as the whitespot itself is under control.

Fish Disease Related Articles:

Perform Regular Water Changes. Because water changes are the first line of defense in dealing with problems such as disease, you want to be able to do large, frequent partial water changes during emergency periods.

Understanding the nitrogen cycle. Fish produce toxic wastes (ammonia) that must be broken down by bacteria through biological filtration. Most fish deaths for first-time aquarium owners are a direct result of not understanding the nitrogen cycle and are completely avoidable.