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Treatment of Common Aquarium Diseases

Does your fish look a little under the weather or does something seem off? In already well-established, well-maintained and fully cycled tanks, diseases are usually not a huge threat, but sometimes some common ailments can still arise, especially when adding new fish.

Avoiding stressful conditions is the key to preventing many diseases, but we’ve compiled a list of some of the most common problems and how to treat them. Keep in mind that most treatments will require the removal of chemical filtration media, such as carbon, from your filter to ensure the medication isn’t removed from the water before it has a chance to take effect. In most cases, UV sterilizers should be turned off as well.

Also, quarantine tanks can be very helpful in the treatment and/or prevention of these diseases. Isolating affected or new fish for treatment in a simple, empty quarantine aquarium is much easier than treating a whole aquarium that may already be full of live plants and other decor that can more easily harbor disease or contaminants making treatment more extensive and lengthy.

Ich, Ick, White Spot (Ichthyophtirius)

This is one of the most commonly seen parasitic diseases in aquarium fish, often seen in “feeders” that are kept in crowded conditions with poor water quality. It appears as small, white spots that look like spots of salt all over the body and fins of the fish. You may notice your fish scratching itself on objects in the aquarium due to irritation. Poor water conditions and/or a rapid rise in temperature or pH can lead to this disease which, if left untreated, can lead to death.


The good news is this one is easy to treat and, since it’s so common, there are many products out there. You can also increase temperatures to 82 Fahrenheit and add aquarium salt to help speed up the lifecycle of the parasite.

Ammonia Poisoning

Just as you can imagine, this ailment simply means there has been an accumulation of excess ammonia and your fish are suffering the toxic effects! Common symptoms are gasping for air at the water’s surface, and inflamed gills. This commonly happens in new fish tank set-ups that were not properly cycled. It can also happen in established tanks if the bio-media containing the beneficial bacteria is jeopardized or if too many new fish are added at one time.


Treatment and prevention is easy! You can test your ammonia levels by using an Ammonia Test Kit and making sure your tank has successfully passed through the nitrogen cycle. You can also use a few easily found products in emergency situations to temporarily reduce ammonia toxicity.

Dropsy, Malawi Bloat

In this disease, fish appear bloated with raised scales and sometimes loss of color. They may also have trouble swimming due to inflation. This is actually a symptom of either a bacterial infection or malnutrition that usually only occurs in already unhealthy or weakened fish, which may stem from poor water quality.


Although medications for this are available, doing 25% water changes every other day to increase water quality can usually help alleviate symptoms. If that doesn’t work, medication should be your next option.

Tail, Fin & Mouth Rot (Fungus)

This infection, usually bacterial or fungal, is a progressive condition that will easily kill your fish if left untreated. Initially, you will notice a grayish white film or growth over the skin and/or tail and fins of the fish which can progress into a more fluffy, cotton-like growth. Fins will become visibly frayed and color may also deteriorate. Fish that are constantly bullied by fin-nipping, especially those kept in poor conditions, are more prone to getting fin rot. If left untreated, it will keep eating away at the fish until it dies.


Antifungal and antibacterial medications can be easily found at your local pet store and treatment is usually successful unless the rot has been neglected for too long and progressed too much.

Body & Gill Flukes

Flukes are flatworms that are approximately 1 mm in length that are commonly present in aquariums but do not cause problems. However, outbreaks can arise from poor water conditions, stress, and overcrowding. Symptoms can resemble ick but one telltale sign is that you may notice movement of the worm or eyespots, which does not occur with ick. Irritated fish will often be seen scratching themselves on objects in the aquarium and have a layer of extra mucus covering the gills or body, inflamed skin, and deteriorated gills. If left untreated, it can easily lead to death, especially when the gills are most affected.


Medications containing praziquantel are most effective and the most readily available.

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