One of the most upsetting things for fish-keepers is the occurrence of disease in our fish and the most common disease, by far, is Ich (or White Spot).
It’s very easy to spot Ich as the fish will be covered in unsightly white spots which usually appear first on the fins and then spread over the body to the gills.
You may first be aware you have a problem if fish begin to rub themselves against the substrate or rocks in the aquarium as they attempt to remove the parasites.
Left alone, Ich can quickly spread to all the fish in your tank and is deadly but treating Ich in your aquarium is both possible and relatively straightforward.
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What Is Ich On Fish
Ich is caused by the parasite, Ichthyophthirius multifiliis, which penetrates and burrows into a fish’s skin or gills and then eats into the flesh. After feeding, the parasite will then detach itself, breed and multiply into thousands inevitably infecting all the fish in your aquarium.
After infection, fish quickly develop the characteristic white spots which spread over the body to the gills which lead to fish initially becoming listless and having difficulty breathing. Eventually, weight loss and death follow.
Fish, under any kind of stress, are most prone to succumbing to Ich as stress weakens the immune system of the fish leaving them less able to fight off infection.
How To Cure Ich in a Freshwater Aquarium
Let’s first look at some ways to prevent ich in a freshwater aquarium.
How To Prevent Ich in a Freshwater Aquarium
Ich is most likely introduced to an aquarium by the addition of new fish so you should closely examine any fish you intend to buy for visible signs or behaviors. If you see any, don’t buy the fish and alert the store owner.
If possible, and you have the facilities, you should quarantine any new arrivals in a separate, quarantine tank for a number of weeks and monitor for tell-tale signs.
If fish in a quarantine tank develop Ich, you can treat them there before transferring them to your main aquarium.
Of course, not everyone is able to do this and, even if you do it’s still possible to get an Ich outbreak.
Ich can also be introduced by plants or snails who may be carrying the parasite even though they are unaffected themselves.
There is also a school of thought that believes that Ich is “ever-present” in water and that stress in fish merely brings it to the fore. If your fish are well fed and healthy and your tank parameters are stable then healthy fish will fight off Ich.
Regular maintenance of your aquarium and equipment means cleaner, more stable, water and a better, healthier environment for your fish.
Fish are easily stressed by temperature fluctuations so make sure you have a good heater and are using a temperature controller.
Freshwater Ich Treatments
If, despite your preventative efforts, you still get an outbreak of Ich, you can treat your aquarium with one of the many anti-fungal agents available at your local fish store or online.
We recommend the one below:-
 | Waterlife Protozin White Spot Treatment | Check pricing on eBay >> *Free UK Delivery |
Note: You should remove any activated carbon during treatment as this will absorb some or all of the active ingredients of the medication.
Follow the instructions carefully and do not overdose.
The dose is calculated based on the volume of your aquarium and then added on days 1, 2 and 3. Then no dose on days 4 and 5 and the final dose on day 6. The final dose should kill any free-swimming parasite young.
As well as removing activated carbon, we also recommend raising the temperature of your aquarium to around 80 degrees Fahrenheit to speed up the life cycle of the parasite and running an air-stone to increase aeration.
How To Treat Ich in a Reef Tank
The problems of Ich in a saltwater aquarium are essentially the same as in a freshwater aquarium except that in a saltwater aquarium with corals you need to take much greater care.
Corals are highly sensitive and would die if subjected to the medication used in freshwater aquariums.
How To Prevent Ich in a Saltwater Aquarium
To prevent Ich in a saltwater aquarium the emphasis is much more on using quarantine or hospital tanks.
Any new arrivals would first be placed in a separate quarantine tank for observation and possible treatment usually with a copper-based medication.
This medication is harmful to corals though, so If you did get an outbreak in your reef tank you would have to remove the infected fish and transfer them to a quarantine or hospital tank and treat them there.
The reef tank would then remain fallow (i.e. empty of fish) for approximately 76 days until all remaining Ich parasites had died off.
As with freshwater, prevention is better than cure, so keep on top of your water parameters and tank maintenance.
Diet plays a very important role as well. Well-fed, healthy fish are much better placed to fight off infection so make sure you do your research on what foods are best for them and include as much variety as you can.
Consider, also, using a food enhancer or vitamin supplement to boost your fish’s immune system. We use the one below with every meal:-
 | Selcon Concentrate | Check pricing on Amazon > |
Contains: Highly Unsaturated Fatty Acids, Marine Lipids, DHA, EPA, Vitamins B & C.
Does not contain yeast, phosphates or nitrates and will not affect water chemistry.
Simply add a few drops as you de-frost frozen food or use to soak dry pellets and flakes.
Saltwater Ich Treatments
As mentioned above, you can treat Ich in your marine fish by first transferring them to a quarantine tank and then treating that tank with a copper-based medication.
There are several available and you can find out more from either your local fish store or online.
What if you don’t have a quarantine tank though?
Well, there is a treatment that you can try that claims not to harm your corals and inverts…
We have used it… And it worked for us… Ich was gone and no harm to our corals or inverts. See below:-
 | MinnFinn Reef Safe Protozoal Treatment | Check pricing on Kraken Corals > |
The treatment is in two parts with part 1 being the medication and Part 2 which then neutralizes it one hour later. Make sure you closely follow the instructions.
MinnFinn also claims to treat Velvet, Flukes, Flatworms and other pests though we have not used it or tested it for those.
You may also wish to consider using a UV Sterilizer to help combat Ich and other diseases. Read our article Why Use a Fish Tank UV Sterilizer to find out more.
For more information on other fish diseases see our articles, Common Tropical Fish Diseases and Treatments and Common Marine Fish Diseases and Treatments.
Treating Ich In Your Aquarium FAQs
What triggers Ich in fish? – Fish under stress can easily succumb to Ich as their immune systems weaken. Stress can be caused by overcrowding, bullying, temperature fluctuations, and poor water quality.
Ich can also be introduced to your tank from outside by adding new infected fish. It can even come into your tank from live plants. So, inspect any new arrivals closely.
How do I get rid of ick in my fish tank? – There are several chemical treatments available but care should be taken before adding them to your tank. Some treatments may harm shrimp and other invertebrates.
Particular care should be taken in a marine tank with corals.
Can I treat a whole tank for ich? – Ideally, yes, you should treat the whole tank as Ich is highly contagious and the eggs can dwell in the sand, gravel, and plants.
If possible, use a quarantine tank and isolate and treat the fish in that. A quarantine tank can also be used for any new arrivals. Keep them in for a couple of weeks and closely watch for any signs of Ich and other fish diseases.