Fish are lovely pets, and when in an aquarium, they are elegant decorations. But then, they are highly susceptible to diseases, primarily when favorable water conditions are not provided. If you have pet fish, here are the common illnesses, their symptoms, and what to do.

1. Dropsy

This is a kidney bacterial infection which causes fluid accumulation and renal failure. The symptoms include bloating and protruded scales, bulging eyes, and swollen gills and glands. The treatment is antibiotics, and to keep the bacteria at bay, proper aquarium hygiene is essential.

2. White Spots

White spot is a parasitic disease which takes advantage of a weak immune system and is easily diagnosed through visible white spots on the fish, which fall off after a day or two, before infecting other fish or the same one. Isolate the fish with white spots, and treat the water with an anti-parasite formula.

3. Fungus

Fungal infections take away the beauty of the fish. The symptoms are whitish or grayish patches on the body, and when left untreated, they turn into hairy mould. The remedy is to use antibiotics and antifungal formula and always ensure proper water quality and hygiene.

4. Fin Rot

As the name suggests, this is a disease which wastes away the fins of your fish, and the symptoms are ragged, decaying, or rotting fins. The disorder is mostly bacterial but can also be caused by improper water pH. Antibiotics will help alleviate the root cause, but it is imperative to ensure proper water quality.

5. Gill Flukes

Gill flukes (Dactylogyrus and Gyrodactylus) are parasites which infest the gills and skin of fish and lead to respiratory complications and distress. The worms may damage the gills and consequently lead to death if not treated promptly. Antibiotics will kill the parasite and manage the condition. Above all, water quality is paramount.

6. Cataracts

This is not only a human eye problem; it also affects fish. A cataract is a fungal infection, and its manifestation is white or gray fungus on the eyes. Over-the-counter antifungal medication will be enough to manage the condition, but also ensure proper water quality to prevent reoccurrence.

7. Anchor Worms (Lernaea)

This is a parasitic worm which buries its head in the tissue and causes severe inflammation and itching on the skin. The fish rubs its body on the walls of the aquarium in a bid to get rid of the worm. Anchor worms are visible, so carefully pull them out and use a topical antibiotic ointment on the area before disinfecting the water.


There you have it folks; seven prominent aquarium fish illnesses. Pet fish are easy to keep but require intensive monitoring and most importantly, favorable water quality. This is the only way to keep those fungal and bacterial infections at bay.