Ich is a very common problem in aquariums and different aquarists adhere to different regimes when it comes to preventing and curing Ich. In this article I will describe a combination treatment that I have had great success with in the past. It involves an increased water temperature, added aeration, aquarium salt and frequent water changes. I will also briefly discuss how over the counter medications that can be used to treat particularly powerful outbreaks of Ich.
Some people prefer to use other forms of treatment, e.g. refraining from increasing the temperature since it places additional stress on the fish. It is hard to know for sure which treatment that is best and the preferable choice of treatment it will also depend on which fish you keep. If you for instance know that your species are extremely sensitive to changes in water temperature, a rapid increase of temperature should naturally be avoided; if you keep salt intolerant species, you must refrain from using salt to cure Ich and so on.
What is Ich?
Ich is caused by a ciliated protozoan of the genus Ichthyophthirius – Ich is simply an abbreviation of the word Ichthyophthirius. Some people prefer to spell it Ick, perhaps because they find the disease icky? Ich is also known as White Spot Disease since it causes small cysts to form on the skin of infected fish. If you look at the protozoan under a microscope, you will see a round rolling mass with a u-shaped nucleus. This parasite is completely surrounded by cilia.
The lifecycle of Ichthyophthirius
The Ich parasite starts its life as a free swimming organism that moves around in the aquarium, looking for a suitable host. When it finds a fish, it will attach itself to the outer layer of the fish's skin and start feeing on its bodily fluids. It can also attach itself to the gills, thus making it hard for the fish to breathe. Soon, the parasite will have developed a protective outer shell, a so called cyst, and it is this shell that we can see as a small white grain on the skin of infected fish. A fish heavily infested with Ich parasites can look as if someone had sprinkled it with grains of salt.
In the encysted stage, the parasite is a so called theront. The theront stage will end when the organism has grown big enough to break through its protective shell and drop to the bottom of the aquarium. It will attach itself to any surface, e.g. gravel, plants, tubing, or glass, and start to reproduce. The theront has now turned into a trophozoite (also known as trophont). Within 36 hours, one single trophozoite can produce hundreds of free-swimming Ich organisms – so called tomites – and the life cycle will start over again. Only the tomites are able to infect fish and only the tomites are sensitive to treatment.
Ich in the wild
Ich is commonly occurring in nature but it poses less of a threat in its natural environment, due to two main reasons. Firstly and foremost, it is much harder for the parasites to find suitable hosts when they have to search a huge body of water. In a small aquarium, virtually every single parasite stands a high chance of stumbling upon a susceptible host.
Secondly, there are more fishes for the parasites to infest in the wild. The risk of one single fish becoming infested over and over again is therefore much lower in a large body of water than in a small aquarium. In a closed system like an aquarium, the parasites will infest the same poor fishes over and over again, gradually weakening them and thus making them even more susceptible to new Ich attacks.
Thirdly, a fish that manages to combat Ich seems to develop some degree of immunity to the parasite. Wild fish that becomes infested by just a few parasites have a greater chance of fighting them off, thereby developing a higher resistance towards new attacks. In an aquarium where a fish might be attacked by hundreds of parasites at once, its chances of successfully fending them off and developing immunity is much less
Completely eradicating Ich from your aquarium is not easy, and studies show that small amounts of Ich tend to be present even in well maintained aquariums where the fish are in prime condition. Just like the immune system of a healthy person can handle a few germs in the air, healthy fish seem to be able to live with Ich around them without falling ill. If we on the other hand crammed that healthy person into a subway and forced him to stand in a crowded wagon filled with sneezing persons, it might soon be too much for his immune system to handle and he would catch a cold. The same thing is true for fishes – if you place them in a crowded environment, rarely perform any water changes and introduce a bunch of diseased specimens, you may very well have an Ich outbreak on your hands. The best way of preventing Ich is therefore to avoid crowding, perform sufficient water changes and quarantine new fish before you allow them into your main aquarium.
In addition to the causes described above, factors that are detrimental to the immune system of your fish can easily cause an Ich outbreak and must therefore be avoided. This includes keeping your fish in a barren aquarium where it feels stressed, keeping it with bullying tank mates, and keeping schooling fish alone. Water temperature and water chemistry should always be maintained within suitable parameters, and do not forget that many species handle rapid changes poorly. Even changes that are within the recommended water parameters can prove harmful to such species. Keeping the levels of organic waste down in the aquarium is also very important if you want your fish to stay healthy.
A lot of fish species can survive in an unsuitable environment, e.g. a barren aquarium where water changes are hardly ever carried out, but it will be unfavorable for their immune system and sooner or later they will probably succumb to a disease such as Ich.
Last but not least, fish that is weakened by other health problems are an easy target for parasites. It is therefore a good idea to move injured and diseased fish to a recuperation aquarium where they can heal. If they turn into a breeding ground for parasites and bacteria, at least they will not infect the rest of your fish.
As long as the Ich parasite is protected inside its cyst, it is virtually impossible to get to - the levels of medication that would be necessary to affect the parasite inside the cyst would kill the fish as well. This is why we must focus on the free-swimming tomite stage when the parasite is much more vulnerable.
- Bring up the water temperature to 85-88 degrees F (if you think you fish can handle it).
- As mentioned above, Ich can attach itself to the gills of fish and make it hard for them to breathe. It is therefore a good idea to increase aeration in the aquarium to keep the levels of oxygen really high. Adding more aeration is especially important if you increase the water temperature since cool water holds more oxygen than warmer water.
- Add roughly one teaspoon of salt per gallon of water. (You can adjust this amount depending on how salt tolerant you fish are.)
- Carry out a series of water changes and clean all the gravel. Changing around 50% of the water once a day is recommended.
- Continue the treatment for at least one week, since you can only kill the free-swimming Ich parasites. The speed of the life cycle is temperature dependant (it will for instance take three days at 80 degrees F) and continuing treatment for an entire week is recommended to be on the safe side.
- If this is not enough to combat the Ich outbreak, you need to visit your local fish store and pick up some anti-Ich medication. Unfortunately, the Ich parasites seem to become more and more resilient towards treatment each year. Lazy aquarists and pet shop keepers are often tempted to constantly use medications to fend off disease, instead of devoting themselves to frequent water changes etcetera, and this makes it easy for resistant strains of parasites and bacteria to develop.
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