Ich, also known as ichthyophthiriasis or white spot disease, is a parasitic disease that affects a wide range of fish species. It is caused by the ciliate protozoan Ichthyophthirius multifiliis.
Ich is found in almost all freshwater and marine environments, and it is one of the most common and widespread diseases affecting commercial and ornamental fishes.
Ichthyophthirius multifiliis causes circular white spots that appear on the skin and gill of infected fish where it feeds on the fish’s blood and tissue. Its a common problem for farm and aquarium fishes that can affect all species.
The article provide detailed information about the causes, symptoms, prevention and treatment of this notorious Ich disease for both culture and aquarium fishes.
What is Ich\White Spot Fish Disease
Ich or white spot fish disease is a common parasitic disease that infects many types of freshwater fish.
Ich larvae enter the fish’s body through the gills and skin and then migrate to the muscles and internal organs where they mature and reproduce.
The white spot on fish is a circular, white lesion that is found on the skin of fish. This small, round spot is located on the fish’s dorsal fin and is usually white or light-colored.
The ick can cause a number of direct and indirect (secondary) problems for the fish, including inflammation, lesions, fungal, bacterial infection and physical injury.
What is Ich (Ichthyophthirius multifiliis)
Ich is the short form of Ichthyophthirius multifiliis, a protozoan (Eukaryote, unicellular) parasite member of the family Ichthyophthiriidae.
The name “Ich or Ick” comes from the disease causing parasite’s (Ichthyophthirius multifiliis) first three letters.
The scientific names comes from Greek words ichthys = Fisch, phtheiros = louse; Latin: multus = much, filia = daughter.
What Does Ich\Ick Look Like on Fish?
In a normal eye view, it looks like white spots on the body, eye, gill and fins of the fish. The spots on fish may be small or large.
In microscope view, it looks circular shaped and has cilia surrounding its body. It has a horseshoe-shaped macronucleus that is typical to it and an identifying feature.
It is a free-swimming ciliated protozoan, has cilia that cover the body completely. The pear-shaped infective ciliated theronts are usually motile and active, approximately 30 to 45 micrometres long.
Susceptible Species | Species Affected
All types of freshwater cultured and aquarium fishes are affected by this parasite.
Often considered a “warm water” disease, outbreaks frequently occur in the spring when the water temperature starts to rise.
In culture species, catfish, carp are usually found to be more susceptible and can be easily affected by Ich diseases. Aquarium (ornamental) fishes are also infected by this disease.
Geographical Distribution
Ich has been reported in fish from all continents, and it is likely present in most countries with aquatic ecosystems.
It is particularly common in tropical and subtropical regions, where the warm water temperatures and high humidity favor the proliferation of the parasites.
Ich outbreaks can occur in aquaculture facilities, public aquariums, and home aquariums, as well as in natural bodies of water.
Ich usually found in freshwater captive fish species and they are very specific to host species and have very low host specificity.
Transmission
Ich parasites can be transmitted from one water body to another or one aquarium to another through several means.
Some common ways that ich parasites can spread include:
Movement of infected fish: If infected fish are introduced into a new water body or aquarium, they can transmit the parasites to the other fish in the system.
Transfer of contaminated water: Ich parasites can survive for a short period of time in the water, so if contaminated water is introduced into a new system, the parasites can spread to the fish in the new system.
Use of contaminated equipment: If contaminated equipment, such as nets, buckets, or filters, is used in multiple systems, it can spread the parasites to the new system.
Transfer of contaminated plant material: Ich parasites can also be transmitted through the transfer of contaminated plant material, such as live plants or decorations.
Transfer of contaminated substrates: Contaminated substrates like, sand, gravel and driftwood carry the parasite.
To prevent the spread of ich, it is important to practice good hygiene and to quarantine new fish before introducing them into an established system.
It is also a good idea to disinfect equipment and plant material before using them in a new system.
Life Cycle of Ich (Ichthyophthirius multifiliis)
The life cycle of ich consists of three stages: trophont, tomont and theront.
1. Trophont
This is the infective stage of the parasite. The trophont is a stationary, feeding stage that is attached to the skin or gills of the fish.
During this stage, the trophont feeds on the blood cells, host’s tissues (cellular debris and live host cells) and secretes a protective cyst around itself.
This stage have a rounded anterior end and a posterior end with a distinct constriction. It contain a single nucleated cell and a prominent nucleus. It lack cilia but have a thin layer of cilia on the outer edge of the body.
Fish infected by trophonts stage become very sick. It causes fish to lose weight and eventually die.
2. Tomont
When the trophont has matured, stops feeding at its environment and detach from the host (fish) and turn into a tomont. A mature trophont lacks the energy to reproduce.
In water, the tomont immediately produces a tomitical cyst that has a tough, gelatinous wall. When the individual encapsulated in cyst it prepare itself for next generation.
Inside the cyst, within days the single tomont cell divide multiple times and produce hundred to thousands of infective, ciliated tomites at a water temperature of 22° to 25ºC (72º to 77ºF).
It’s important to note that Ich can also reproduce asexually, through a process called binary fission. This allows the parasite to rapidly increase its population size, which can lead to outbreaks of disease in fish populations.
3. Theront
Theronts begin to develop within the tomont cyst and develop into larval theront within a tomont. Theront development within these cysts occurs over 1 (warm water temperature) to 3 week period (cold water temperature).
The released or hatched larval form is called a theront. The theront is a swimming, motile, nonfeeding stage of the parasite.
The theronts are pear shaped and range in size from 0.1 to 0.3 millimeter in diameter. These young are transparent and move rapidly along the length of the body.
The released theronts desperately swim in the water 2-3 days for their next host.
Interesting fact is, if they do not manage to find their next host within this short time frame, they will die and their life cycle will not be fulfilled.
However, once they find their host immediately they attach on their skin and burrow onto its epithelial tissue (outer covering of the skin).
The epithelial tissue covers the entire body’s surface, and it guards the body from mechanical injury, chemical exposure, excessive fluid loss, and infection.
When the dig into the fish epithelium, the theront will eventually develop into a trophont and the cycle will start again.
Cause of Ich or White Spot on Fish | Factors Facilitate the Occurrence of Ich
–The causative agent of white spot disease is Ichthyophthirius multifiliis. The parasite can be introduced into a fish tank through new fish, untreated water, or food.
There are several factors that can contribute to the presence of ich in an aquarium and commercial water body. These factors are,
Poor Water Quality
Poorly maintained tanks with low or high pH, high levels of ammonia and nitrite can weaken fish and make them more susceptible to ich.
Stress
Fish that are stressed due to overcrowding, poor nutrition, or other factors may be more likely to develop ich.
Temperature
Ich tends to thrive in cold water, so keeping the temperature of the tank too low can increase the risk of an outbreak.
Poor Tank Hygiene
Dirty tanks and equipment can harbor ich parasites and lead to an outbreak. Net and hoses may transfer the parasite one tank to another.
Inadequate Quarantine
Introducing new fish or fry to the tank without properly quarantining them can allow ich parasites to enter the tank.
Overcrowded Fish
The illness is comparatively severe when fish are overcrowded.
Immunity
Some fish may have a natural immunity to ich, while others may be more susceptible.
Signs & Symptoms of Ich on Fish | Symptoms of White Spot Disease
-The most obvious is the presence of white spots on the fish’s body. These spots are actually the parasites, which can range in size from very small to visible to the naked eye. The spots may grow and spread until large areas of the body are covered.
-Ich on fish eye, Ich on fish fins were observed. In severe cases, lesions or sores on the body of the fish, inflammation around the eyes.
-Fish will become pale or gray colored at the same time fish rubbing body with hard substrates.
-Behavioral changes of affected fish: Lethargy, loss of appetite, abnormal breathing, irregular swimming or inactivity are common signs of ich. Fish often swim very slowly or rest at the bottom of the tank.
Diagnosis of White Spot Disease
The parasites attach themselves to the fish and secrete a feeding tube, through which they extract nutrients from the fish’s tissues.
The parasite is usually diagnosed by microscopic examination of infected tissues. Use a microscope to look for the telltale white spots on the fish’s body.
Even in advanced stages, the parasites will first analyze the skin of the fish and cause paradoxical rubbing, or even small white cysts to appear in the surface, including their gills.
How To Prevent Ich on Fish
Prevention of ich is the best course of action, and there are several things that can be done to reduce the risk of a fish becoming infected.
By following these steps, you can help to prevent ich and other diseases from affecting your aquarium fish.
Separate Infected Fish
Remove affected fish from the tank and treat them in a separate container with medication. The water in the main tank should then be treated with similar medication.
It is also important to clean all of the equipment in the tank and replace the water with fresh water. The quarantine period helps prevent the spreading of the disease.
Quarantine New Fish
Quarantine new fish for at least two weeks before introducing them to your main tank.
This will allow you to monitor them for any signs of disease, including ich, and treat them if necessary before they have a chance to infect your other fish.
Avoid introducing wild fish or plants to your aquarium, as these can be carriers of diseases such as ich.
Maintain Good Water Quality | Keep Aquarium Clean
The most important step is to maintain good water quality if you notice ich. A clean, healthy aquarium is less likely to be affected by ich and other diseases.
Keep your aquarium clean and well-maintained by performing regular water changes, keeping the tank free of excess food and debris and maintaining the proper pH and temperature.
Make sure your tank or water is properly cycled and filtered, and keep the water temperature within the appropriate range.
Avoid Overstocking
Avoid overstocking your tank, as overcrowding can lead to increased stress and a higher risk of disease.
Provide Provide Nutritional Diet
Another important step is to provide your fish with a healthy diet. Feed your fish a varied diet of high-quality, nutritious foods to help boost their immune system and make them less prone to illness.
If you have an ich outbreak in your tank, be sure to treat all of your fish, even if they don’t appear to be affected.
Ich is highly contagious and can spread quickly through an aquarium, so it’s important to treat all of your fish to ensure that the disease is fully eradicated.
How Treat Ich on Fish (Ich Medication) | How to Cure Ich on Fish
It’s advisable to treat infectious theronts and reproductive tomonts when they’re still in the water and before they have the opportunity to penetrate the fish as trophonts.
Free swimming infective theronts are susceptible to chemical treatment. Chemical treatment have to done to control free-swimming theronts by applying chemicals.
Increase Water Temperature
Water temperature is a crucial factor for the control of these parasitic worms. Warm water helps kill Ich.
Raising the water temperature several degrees Celsius above normal raising the water temperature for 5 to 7 days hampers the growth of pathogens that are sensitive to heat and boosts the immune response of the host.
Regular Water Exchange
The most important step is to improve water quality by doing regular water changes and add filtration system in water body.
You can also help reduce stress on your fish by providing a stress-free environment and avoiding sudden changes in temperature.
Perform a partial water change and clean the filter to remove any excess medication and parasites from the tank.
Continue to monitor your fish closely and treat for an additional 3-5 days after the visible signs of ich have disappeared to ensure that all of the parasites have been eliminated.
Chemical Treatment
To a significant extent, all anti-ich chemical substances have formaldehyde, malachite green, copper sulfate, or a combination of one or more of formaldehyde, malachite green, copper sulfate, and malachite green.
Formaldehyde at 0.25 ppm (1 ml/10 gallons) is effective if administered three times on alternating days.
Formalin is also used as an effective treatment against this parasitic disease. But in the case of low dissolved oxygen levels, formalin is not suggested. 0.1 ppm malachite green (zinc-free) is used for treating sick fish.
Salt Treatment
The most common way which is mostly applied in aquarium water for treating ich is salt treatment.
Adding 1-3 tablespoons of salt per gallon of water can help kill the parasite. Make sure to monitor the salt levels in your tank, as too much can be harmful to your fish.
Copper Sulfate
Copper sulfate will kill the parasites when they come into contact with it. This can be added at a rate of 0.25 – 0.5 mg/L for 7-10 days.
White Spot But Not Caused By Ich
White spots on fish can be caused by a variety of things, including parasites, fungal infections, and physical injuries. If the white spots are not caused by ich (also known as white spot disease), it is important to determine the underlying cause in order to properly treat the condition.
Some possible causes of white spots on fish include:
Velvet disease: A parasite that causes small, gold or brown spots on the skin of fish.
Columnaris: A bacterial infection that causes white patches or lesions on the skin or fins of fish.
Fungal infections: Fungal infections can cause white or gray patches on the skin or fins of fish.
Physical injuries: Physical injuries, such as cuts or abrasions, can also cause white spots on fish.
If you are unsure of the cause of the white spots on your fish, it is best to consult with a veterinarian or a fish health expert for a proper diagnosis and treatment plan.
Frequently Asked Questions (FAQs)
Can white spot affect humans?
Ich parasites do not infect humans and cannot be transmitted to humans from fish.
However, humans can be infected with other parasites that may be transmitted through fish, such as tapeworms and certain types of flukes. These parasites typically require intermediate hosts, such as snails or crustaceans, to complete their life cycle.
Humans can become infected if they eat raw or undercooked fish that is contaminated with these parasites. To reduce the risk of infection, it is important to cook fish thoroughly and to practice good hygiene when handling raw fish.
Can white spot kill fish?
Ich can be a serious and potentially fatal disease for fish. The parasite interfere with the fish’s ability to breathe and regulate its body temperature, which can weaken the fish and make it more susceptible to other diseases.
In severe cases, ich can lead to significant morbidity and mortality in fish. The mortality rate may vary depending on the species of fish, the level of infection, and the overall health of the fish. Some fish, particularly those that are stressed or immunocompromised, may be more vulnerable to the effects of ich.
How long does ich stay on fish?
The ich life cycle is relatively short, lasting only about 10 days, but during that time the parasite can infect and kill vast numbers of fish.
In conclusion, ich is a common and highly contagious parasitic infection that affects fish. It is important to be vigilant in detecting and treating the disease in order to prevent it from spreading to other fish in the tank.
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