fish diseases

Types of aquarium fish diseases

Watching your aquarium fish get sick and eventually die of a disease you do not understand can feel extremely tragic. Having some idea about the problem is a first step to preventing such scenarios and allowing your aquarium fish enjoy a long lifespan.
Note though, that this is just a guide and it is always best to consult your local fish store for any disease diagnosis and treatment. Here are a few common aquarium fish diseases and care.


A fish is more susceptible to dropsy when it has been weakened by stress. It is a bacterial infection of the kidneys which leads to renal failure or fluid accumulation.


Pale gills, bulging eyes, inflated belly, protruding scales, damaged fins and inflamed anus.


Untidy aquarium conditions such as poor water quality, poor nutrition and spike in ammonia or nitrite, or a drastic change in temperature are believed to be major causes.

Prevention and Treatment:

Maintaining proper environmental conditions in your aquarium is key to preventing dropsy. Do not overcrowd your tank, leave it dirty or overfeed your fish. Change water regularly.

If disease is already present, move the affected fish to a different tank to prevent the spread and euthanize it. Add one teaspoon of salt to every gallon per day and keep tank clean.


ICH is a fairly common disease encountered by hobbyists. It is also known as White Spot disease and can be fatal if not properly taken care of.


White spots resembling salt grains; scratching against objects due to irritated skin; clamped fins.

Stress (such as from overcrowding, temperature fluctuations and pH instability) which compromises the immune system.

Prevention and Treatment:

Keep water parameters (such as temperature and pH) stable, as well as environmental conditions. Purchase only healthy fish.

Immediately isolate any infected fish and make use of ICH medication gotten from your local fish store. Administer according to prescribed instructions. It is considered best to treat the entire aquarium fish due to the infectious nature of ICH.

Fin Rot

A treatable but very common aquarium disease; fin rot is a progressive deterioration of the fins. Left too long, it could be deadly.


Fins turn white as their color begins to fade. Fins may also appear frayed, inflamed, opaque, or even blood streaked.


Aquariums with poor conditions which are overcrowded, or are belied by the presence of fin-nipping fishes, expose aquarium fish to fin rot. Poor water and food quality could also contribute.

Prevention and Treatment:

Keep temperature and pH levels at the ideal level for fish survival. Do not overcrowd your tanks and maintain proper hygiene measures.

Anti-bacterial drugs such as Oxytetracycline, Tetracycline and Chloramphenicol could be administered to cure fin rot. See a local fish store for specific dosage. Add aquarium salt and change water often.

Body Flukes

Tiny worm-like parasites that get under fish skin and into the gills and other body parts are known as Flukes (Body Flukes, Gill Flukes or Skin Flukes).


Fish scratching against objects in the tank due to irritation, abrasions, minimal fish movement, small blood spots, rapid respiration, layers of mucus on gills or body, etc.


Stress, incompatible tank mates, overcrowding and poor water conditions.

Prevention and Treatment:

Quarantine all new fish before introducing them into your tank to prevent body flukes. Check all live foods fed your fish for flukes.

Flukes can be eliminated from fish through antibiotic treatment. Your local fish store could help with more precise prescriptions.

Final Notes

A repetitive word of note has appeared in all treatment guides presented here. Drug prescription is best administered by someone who can verify directly the condition of your fish. In the end, though, prevention is the best policy. Add aquarium salt to desired levels, keep pH levels stable and ideal, actively regulate tank temperature, and only include healthy and compatible fish in your aquarium. Your aquarium fish can live long and healthy lives.