Ich sometimes resembles a fungus, though it’s an external protozoan parasite. Ich’s full name is Ichthyophthirius multifiliis. The Latin name translates to “fish louse with many children.”
Ichthyophthirius multifiliis is present in freshwater fish. Saltwater fish develop a type called Cryptocaryon irritans.
These parasites have short, hair-like cilia that vibrate and help the organism move.
Ich is one of the most common parasites in freshwater aquarium fish and one of the most treatable. One reason it’s easy to treat is because it’s visible — aquarists can often spot it before the infection gets too bad.
Ich parasites can grow up to 1 mm in diameter. Most other parasitic infections are more challenging to spot.
The Life Cycle Of Ich
Parasites have several life stages, and treatment is only effective during certain stages.
The Trophont Stage
The parasitic “trophont” stage is when the parasite is visible. The trophont appears as white, salt-like specks on the fish’s bodies.
During this stage, the parasite feeds off the fish’s epithelium. The epithelium is a thin layer of tissue that protects the inside and outside of the body.
Trophonts are resistant to treatment because the fish’s slime coat protects it.
Trophonts are highly harmful, causing major tissue damage as they eat at the fish’s bodies. Trophonts can lead to death if the infection goes untreated and continues spreading.
Many aquarists make the mistake of only treating ich when it’s visible. They stop treatment once the white spots disappear, assuming the infection is gone.
Unfortunately, these aquarists stop treatment at the most crucial time. Simply because the parasites are no longer visible does not mean they are no longer present.
Aquarists should continue their ich treatment for about a month. The time frame ensures treatment attacks the parasites during the right life stage.
The Tomont Stage
After feeding on the fish, the trophont falls off the fish. It begins the process of becoming a tomont.
Trophonts attach themselves to the sides of the aquarium. They also stick to the substrate, plants, and decorations.
After attaching to a surface, trophonts produce a cyst wall, becoming a tomont.
Tomonts reproduce by continually dividing themselves. A single cyst can produce between 100 and 1,000 new parasites, called theronts.
The Theront Stage
Theronts are infectious. They push their way out of the cyst and become free-swimming larvae. They swim about the water column until they find an organism to infect.
The theront life stage is the only one that is vulnerable to treatment.
Theronts can only survive for two to three days without finding a host.
Their short lifespan is why it’s essential to quarantine infected fish away from the main tank. Keeping the main tank empty for a few weeks ensures that all the parasites will die off.
After treatment, fish can safely return to their main tank without risking reinfection.
Here Is What Ich Looks Like
Ich spots look like tiny grains of salt that cover the body, fins, and gills of fish. The spots are uniformly round and don’t have fuzzy-looking growth like fungus.
There may only be a few spots when the infection is new. As the infection spreads, more white spots appear on the fish. Severe infections may cover the majority of the body.
Sometimes ich may begin on the gills, making it difficult to spot. Once the caretaker notices spots on the rest of the body, the fish is already more ill. That’s why looking out for symptoms other than the white spots is important.
Ich Symptoms
The small white spots of the parasite are the most obvious symptoms of ich.
Other symptoms include the following:
- Flashing: rubbing against objects to relieve itchiness and discomfort
- Bruising & scale loss due to flashing
- Lethargy
- Hiding
- Swollen & pale gills
- Loss of body color
- Loss of appetite
- Clamped fins
- Drooping fins
- Rapid breathing
- Gasping for air
- Death
Many aquarists mistake ich for other issues. Fish often receive the wrong treatment or no treatment at all.
Ich is often mistaken for fungus, and antifungal medications will not affect ich.
Breeding tubercles on male goldfish resemble ich spots. Ray fractures may cause spots that look like ich, though they are not life-threatening. The viral disease Lymphocystis also causes white spots that look like ich.
Consult an aquatic veterinarian when in doubt.
Causes Of Ich
The most common cause of ich is the introduction of infected fish to healthy fish.
Always quarantine new fish for four to six weeks before introducing them to the main tank. The quarantine allows enough time to watch the fish and spot signs of illness.
Treat the fish before adding them to the main tank. Doing so prevents the fish in the main tank from contracting the infection.
The same applies to new plants. Treat and quarantine plants before adding them to the main tank.
It can take several weeks for the visible symptoms of ich to appear. Infected fish may appear healthy because they are not in the visible life stage. That is why quarantine must last for at least four weeks.
Cross-Contamination
Another common cause of ich is cross-contamination. Aquarists will sometimes use the same equipment between tanks to save money.
Sharing equipment can transfer ich from one tank to another. It can also happen when moving these things between tanks:
- Infected filter media
- Decorations
- Water
Ich is only sometimes visible; aquarists may use infected equipment without realizing it.
How To Treat Ich
Treat ich by using a medication, salt, and raising the water temperature. Begin treatment immediately upon noticing an ich infection.
The parasites reproduce rapidly. It’s imperative to begin killing the organisms before they have a chance to spread.
It’s always best to consult an aquatic veterinarian before starting any treatment.
Many illnesses and infections share the same symptoms and are challenging to differentiate. A veterinarian can diagnose the right condition and prescribe the right treatment.
Raise The Temperature
The first thing aquarists should do to treat ich is raise the temperature in the tank.
The life cycle of ich is longer in cold water and shorter in warm water.
A single ich trophont can produce up to a thousand new parasites in under 24 hours at the right temperature. The perfect temperature for ich reproduction is 72-77°F (22-25°C).
To be most effective, hobbyists must raise the temperatures to 86°F (30°C), as long as the fish can tolerate it.
Only raise the temperature by 1-2° a day; too fast of a change will likely shock the fish.
Ensure the fish species can tolerate warmer temperatures before raising them.
Cold-water species may be unable to handle warm temperatures. Raising the temperatures will do more harm than good by causing stress.
Even if a fish can’t tolerate temperatures of 86°F (30°C), raising it as much as possible is beneficial. Increasing the temperature shortens the parasites’ lifespans and makes treatment more effective.
Ich can only live for five to seven days when the temperatures are between 72-77°F (22-25°C).
Their lifespans begin to lengthen as the temperature drops. At cold temperatures — 48-50°F (9-10°C) — ich parasites can live for three weeks.
Medication
Anti-parasitic medication is the most effective treatment for moderate to severe infections.
The most effective anti-ich medications contain one or more of the following ingredients:
- Copper sulfate
- Formaldehyde
- Malachite green
- Methylene blue
- Potassium permanganate
These medications can be deadly to invertebrates and “scaleless” fish, like loaches. Salt is also dangerous.
Raising the temperature is the safest method for treating these kinds of organisms. *
Follow all directions on the bottle of medication. Not following directions can leave treatment ineffective and allow the infection to spread.
Use The Right Dose & Remove Activated Carbon
Be sure to measure the correct dosage and remove activated carbon. Overdosing can be fatal to fish while underdosing likely won’t be fatal to ich. Activated carbon makes medication ineffective.
How Long To Treat
Treat the tank for 10 to 14 days to ensure the medication attacks the parasites at the right life stage. Remember that treatment is only effective during the theront life stage.
Quarantine Sick Fish
Treating sick fish in a quarantine tank when using medications is best. It’s detrimental for healthy fish to have exposure to medications.
Leave healthy fish in the main tank. Slowly raise the water temperature to kill any parasites that may be there.
* TIP
Some researchers believe medications may possibly kill ich during the trophont phase. The issue is that the chemical concentration must be very high to kill the parasites.
Fish with ich infections are weak and rarely withstand such high medication concentrations. *
Aquarium Salt
Using salt to kill ich parasites is often safer than medication. Use salt when dealing with minor to moderate infections.
Aquarium salt is effective because it targets parasites. It also boosts the health of the fish.
Pick The Right Salt
Only use aquarium salt. Do not use table salt or marine salt used for saltwater aquariums. Carefully read the directions about mixing and adding salt to an aquarium.
Salt Doesn’t Evaporate
Note that salt does not evaporate. Do not add more aquarium salt without doing a water change. Water changes remove some salt, though not all.
Salt Is Bad For Some Species
Be careful about using aquarium salt with certain species. “Scaleless fish,” invertebrates, and plants are sensitive to salt — its use can be fatal.
After Treatment
Check the fish for white spots after treatment to ensure it was effective. Hobbyists must resume treatment if the white spots reappear.
Reinfection Is Rare
Fish that survive ich infections are less likely to develop an infection again.
Their immune systems respond to the infection by learning how to prevent it in the future. Their bodies create antibodies. The antibodies quickly attack the parasites if they try to reinfect the fish.
The antibodies seem to paralyze the theronts so they can no longer swim. They also cause the parasites to leave the fish’s bodies to prevent tissue destruction.
How To Prevent Ich
The best way to prevent ich is by quarantining all new fish and inverts for four to six weeks.
Buy Healthy-Looking Fish
Buy fish in-store rather than online. Doing so allows the aquarist to look at the fish for signs of illness or infection. Never pick fish that have physical or behavioral signs of disease.
Ich is only visible for one-third of its life, meaning visual inspections aren’t foolproof. They still reduce the chances of buying sick fish.
Quarantine New Plants
Quarantine all plants for two weeks.
Keep plants in a separate tank from new fish or inverts. Without any organisms to feed on, the parasites will die off.
Ich parasites usually die within two to three days without any fish to feed on. Quarantining plants for up to two weeks lessens the chance that there are any survivors.
Don’t Share Equipment Between Tanks
Use different equipment for each tank, including gravel vacuums, nets, and algae scrubbers.
Clean New-To-You Decorations
Thoroughly clean all decorations that are not brand new.
Many hobbyists buy used decorations from yard sales or online sites. Others collect driftwood and rocks from their backyards, streams, or forests.
These practices are great for saving money. They also increase the chance of contamination.
Clean and quarantine such decorations for a couple of weeks before using them. Let them dry out completely for two days before adding them to the main tank.
Keep Water Parameters Healthy & Stable
Ensure the water in the tank stays healthy and within the ideal ranges of the species living there.
Poor water quality and the wrong water parameters cause stress in fish. Stressed fish have lowered immune systems and are far more susceptible to infection.
Provide A Nutritious Diet
Feed fish a varied, nutritious diet that is ideal for their species. A healthy digestive system is vital to fighting off illness and infection.
Check On Fish Everyday
Most fish die from ich infections because their caretakers don’t notice it early enough. A fish has a better chance of fighting off a mild infection than a severe one.
Check on fish at least once a day. Look at their bodies for signs of infection. Watch their behavior and ensure they are acting healthy. They should not be flashing, having trouble breathing, or acting lethargic.
FAQs
Can Ich Affect Humans?
Ich is not contagious to humans. Hobbyists should still clean their hands after working with an infected tank.
Cleaning up is especially important before working with another tank. Otherwise, healthy tanks can become infected with the parasites due to contamination.
Is Ich Always Living In Aquariums?
Whether ich is always present in a tank is highly debated amongst hobbyists.
All aquariums have some type of parasite present in their waters at all times. Healthy fish living in a healthy environment can fight off these parasites.
The parasites become a problem once the fish becomes stressed or ill. They can no longer fight off the inevitable infection.
Aquarists should always treat their aquariums like they have parasites. Meaning, they should keep the water parameters healthy and stable. Keeping the environment healthy almost always prevents fish from getting sick.
Will Ich Go Away On Its Own?
Ich will go away on its own if the aquarist removes all animals from the tank. Without fish or invertebrates to feed on, the parasites cannot survive.
Ich will not go away without treatment as long as fish or invertebrates are in the tank. Ich needs flesh to survive. As long as animals are in the tank, the ich parasites will continue reproducing.
