White Spot or Ick is a common but easily curable fish disease
White Point
White spot disease is caused by a parasite called Ichthyophthirius multifilis. This disease is also called Ick or occasionally Ich or Ichy.
Symptoms
The fish has white spots on the skin. The spots are about the size of the head of a pin and the fish may look as if it has been sprinkled with salt or grains of sugar. The parasite also attacks the gills of fish. This is harder to see. The gills may look redder than normal, but this is difficult to see, and excessively red gills can be caused by a number of things. The gill infection makes it more difficult for fish to take up oxygen from the water, and infected fish may show signs of oxygen deprivation, such as “gasping” at the surface, or apparently very rapid breathing. This oxygen shortage can be caused by many things.
Sometimes fish swim down and try to rub their skin against objects. This is called “flickering” and can be caused by any skin irritation.
Sometimes the fish show no obvious symptoms, but simply die. If a fish dies, you should watch all the fish in the tank very closely.
Omnipresent
This is a very common fish disease. The parasite is present at low levels in most aquariums, often without causing any problems. Most fish have been exposed to this parasite and have developed some immunity. Those fish that have been raised in the complete absence of the parasite will not have this acquired immunity and will be very vulnerable to infection.
The claim that this parasite is present in most aquariums is often misinterpreted. Ichthyophthirius Multiphilis it cannot remain dormant for long periods. He survives by living off the fish. An aquarium can be empty of fish for a month. I would be free of the white spot parasite. A fish that was free of any visible disease was then purchased and then quarantined. This fish could enter the empty tank and develop a white spot. One could erroneously conclude that the empty tank had an inactive white spot or that the quarantine was not done correctly.
What actually would have happened would simply be that the fish had a white spot infection without any symptoms. A successful parasite does not make its host sick. If the parasite were to kill all the fish in the aquarium, pond, or lake it was in, the parasite itself would also die. In nature, the white spot parasite is apparently successful and most of the time does not kill its host. In the unnatural ecosystem of an aquarium, you can easily lose your balance and kill all the fish. This is not only fatal to fish; it is also fatal to the parasite.
The ideal parasite is one that actually gives its host some advantage. To the best of my knowledge, having the white spot parasite is not an advantage to the fish, but other parasite/host relationships may have become symbiotic relationships where both organisms gain an advantage.
Stress
If something stresses the fish, their immune systems often become less effective. The same effect can be observed with people. You are much more likely to have minor and major illnesses when you are under stress.
There are many things that can stress your fish. A very common one is simply being caught, put in a plastic bag, and transported to a new home. A common time for a White Spot outbreak is right after a new fish has been added. Some people incorrectly assume that the new fish has introduced the parasite. They can then go back to the store they brought it from and see that the tank the fish came from is perfectly fine.
Other types of stress include changes in temperature, pH, dH, or any other parameter of the water.
Life cycle
Ichthyophthirius Multiphilisit is an obligate parasite. This means that it can only live in the presence of fish. The actual visible white dots are the feeding stage, called the trophont. The trophont grows and then falls off the fish, falling to the bottom of the tank and forming a cyst called a tomont. Within the tomont up to 1000 tomites can be formed. The tomont opens and the tomites go into the water.
The time it takes to Ichthyophthirius Multiphilis to complete its life cycle depends on the temperature of the water. At 6 degrees C (43 degrees F) it completes its life cycle in about 55 days, while at 29 degrees C (84 degrees F) it completes its life cycle in only about 4 days.
The tomites have to find a fish quickly or they will die. At normal tropical fish tank temperatures, they only have about 2 days to find a fish to infect.
Treatment
The trophont of the fish probably cannot be treated successfully, although claims of successful salt bath treatments have been made. Tomonts at the bottom of the tank are also hard to kill, although they can be removed by washing with gravel. Keeping the tank clean will help.
The only stage that is easily amenable to treatment is free-swimming tomite. This can be removed by many things, including heat, ultraviolet light, salt, and many other chemicals.
There are many possible forms of treatment. All the different ways of eliminating the parasite have the problem that there are many strains of this parasite and they vary in their susceptibility to treatments. Here are some of the ways to treat this disease:
Medicine
There are many commercial treatments for white spot. They usually use some combination of chemicals like methylene blue, malachite green, formaldehyde, acriflavine, etc. In our own tanks, my drug of choice is Wardley Ickaway, but different people will have their own preferences.
Please note that these medications are absorbed by the activated charcoal and if you have charcoal filtration, it will need to be turned off. Most medications are also destroyed by UV light, so the UV sterilization will need to be turned off as well.
Tetras and other characins, scaleless fish such as loaches and catfish, as well as baby fish, are more susceptible to many of these drugs and should be used at half the normal dose. You can use half the rate at twice the normal rate.
Heat
The life cycle of this parasite is greatly accelerated by heat. Increasing the temperature will make the chemical treatments work faster, but it will also mean the infection will spread faster.
However, if the temperature gets high enough, the parasite cannot reproduce and the infection can be cured simply with heat. But some types of fish cannot survive the temperature necessary to destroy the white spot. To break the life cycle of this parasite it is necessary to raise the temperature to about 30 degrees C (86 degrees F). To really kill the parasite, you need to raise the temperature to about 32 degrees C (89.6 degrees F). This temperature should be maintained for at least four days to have a good chance of killing the parasite. Not all fish can survive this treatment, and many that can will be severely stressed. More aeration will be needed because oxygen does not dissolve as much in warm water and the metabolism of fish increases as the water warms so they need more oxygen.
This method of treatment is sometimes the method of choice if you are treating labyrinth fish such as Siamese fighting fish, gouramis, or paradise fish. These fish can survive the necessary temperatures and can breathe air and water.
Chlorine
Some people have reported success in treating this condition through the careful use of chlorinated tap water. Personally, I wouldn’t try this, and I advise other people not to try it. The actual level of chlorine in tap water varies, not only by location, but also by day of the week and season of the year.
Apart from the difficulty of getting the Chlorine dose right there is the problem that some places, like Adelaide Hills where I live, have Chlorinated water. This is deadly to fish and I wouldn’t risk using the water without dechlorinating it.
Salt
Salt will kill the white spot parasite, but different strains have different tolerances. Most white spot strains will kill with 3 grams per liter of salt, but to be safe you’ll need to use 5 grams per liter.
This means that many common aquarium fish cannot survive the level of salt needed to kill the white spot. Generally this method of treatment is not suitable for fish from places without much salt in the water such as the Amazon, Congo and Orinoco rivers.
It can be used on livebearers such as Guppies, Mollies, Platies and Swordtails. It can also be used with some of the Australian fish such as Murray Cod, Silver Perch and Callop, but not safely with Rainbowfish.
Most aquarium plants will die at this level of salt.
ultraviolet radiation
Ultraviolet light will kill the free-swimming thyme stage of the parasite, but can only work on the thyme actually sucked through the ultraviolet sterilizer. You are more likely to get good results if the UV unit is more powerful than is normally recommended for your aquarium size.
An ultraviolet filter will help prevent white spot, but cannot be relied on to cure it.
disease free fish
It is possible to raise fish in the complete absence of the white spot parasite. This is the case with many of the live carriers bred in Malaysia. These fish are raised in water that is a mix of freshwater and seawater, sometimes having up to half the salt concentration of pure seawater. These fish will never have been exposed to white spot or other diseases and will be highly susceptible to them. These fish can disappear quickly. If purchased, they should be observed and treated promptly as needed. Aquarium stores will usually advise their customers that the fish are free of disease.
Secondary infections
White spot infection damages the skin of fish and it is common for bacterial or fungal infections to occur along with white spot.
susceptible fish
Some types of fish get white spot disease more easily than others. Clown Loach have a particularly bad reputation for contracting this disease.