Most Common Tropical Fish Pests & Diseases (with solutions!)

Goldfish with Ich

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Unfortunately, no matter how much time and care we take looking after our fish, there are occasions when they become sick or attacked by a pest. In this article, I look at some of the most common pests and diseases to affect our fish and offer solutions based on my 30+ years in the hobby.

Some of the treatments I look at are based on medications available from your local fish store, whereas others are based on making a change in your aquarium to help your fish fight off the disease naturally.

Most Common Tropical Fish Pests and Diseases

In no particular order, the table below shows some of the most common pests and diseases that we can come across in our fish tanks, what the symptoms are, and a recommended treatment.

For more information on any of the specific pests or diseases, click on the name of that disease to be taken to a dedicated article I have written.

DiseaseSpecies AffectedCauseSymptomsTreatment
Ich (Whitespot)AllIchthyophthirius multifiliis parasiteSmall white spots on fins and bodyUse commercially available treatment such as Ich-X and raise the water temperature
Fin RotAllBacterialFin edges becoming ragged and erodingRemove fin nipping fish, improve water quality, treat with an anti-fungal treatment
DropsyAllMultiple different causesSwollen, bloated body with scales sticking out (pinecone)Treatment varies depending on the cause of the Dropsy
Internal TapewormsAllInternal parasiteThin, lethargic fish, losing weight even though they are eatingCommercially available treatment for internal tapeworms and parasites such as Paracleanse
Columnaris (mouth fungus)AllFlexibacter bacteriaWhite, cotton wool-like growth, especially around the mouthUse commercially available treatments and improve water quality
Swim Bladder DiseaseAllBacterial infection or digestive issuesInability to stay upright in the waterTreatment may be possible depending on the cause
Saprolegnia FungusAllFungusWhite, fur-like growthsCommercially available treatments
Malawi BloatAfrican Cichlids, especially from Lake MalawiIncorrect diet, stress, Similar to DropsyFeeding a diet high in fiber
Hole-in-the-headSouth American CichlidsHexamita parasiteUlcer on the head-turning into a hole if left untreatedCommercially available treatments such as MetroPlex
Neon Tetra DiseaseAllPleistophora hyphessobryconis ParasiteColor loss, weight loss, curved spineNo known cure
Anchor WormsAllLernaea parasiteParasite physically attached to the bodyPhysically remove parasite and treat to prevent secondary infection
Gill or Skin FlukesAllGyrodactylus and Dactylogyrus parasitesDifficulty breathing, fish rubbing body against decorations and tank sidesCommercially available treatments such as Hikari PraziPro
Velvet DiseaseAllOodinium parasiteGolden spots on the body, fish rubbing against decorations and tank glassCommercially available treatments such as Cupramine
Piscine TuberculosisAllMycobacterium marinum bacteriaNon-specific, sporadic fish deaths, susceptible to secondary infectionsNo treatments are currently available
VibriosisAllVibro bacteriaRed fins and mouth, bulging eyes, lack of energyNo commercially available treatments
PseudomoniasisAllPseudomonas bacteriaFin erosion, lack of energy, body ulcers, death
IridovirusGouramis, Angelfish, Dwarf CichlidsVirusLoss of color, swelling, loss of appetite, lesions on the bodyNo known cure
LymphocystisAllVirusCauliflower like growths around the eyeNo known treatment

Further Reading

I have created a dedicated article discussing each of the pests and diseases above, detailing the symptoms, causes, treatment, and prevention for each disease.

Click on the name of each disease in the table above to be taken to that specific article.

About the Author

I’ve been keeping, breeding, and showing tropical fish for nearly 30 years. Over that time I’ve done it all! I’ve had great success and I’ve made some really foolish mistakes (like the time I bought an Asain Walking Catfish). Read more…
Richard James