Fish disease library

Browse every disease, parasite, and bacterial infection covered in our knowledge base. Pick filters to narrow it down — results update as you go.

19 conditions

Goldfish

Bacterial Diseases in Koi & Goldfish

Bacterial diseases are among the most common and serious health challenges facing koi and goldfish keepers worldwide. Caused…

Moderate To To To Severe

Goldfish

Parasitic Diseases in Koi & Goldfish

Parasitic infestations represent one of the most diverse disease categories in ornamental fish keeping. From the microscopic ciliate…

Mild To To To Severe

Goldfish

White Tail Disease in Koi & Goldfish

White tail disease is a serious and poorly understood condition caused by microsporidian intracellular parasites that destroy muscle…

Moderate To To To Severe

Freshwater Tropical

Columnaris

A highly contagious bacterial infection (Flavobacterium columnare) presenting as white/grey patches, often on the mouth, fins, or gills.…

Severe

Freshwater Tropical

Aeromonas (Ulcer Disease)

Bacterial infection causing open ulcers, hemorrhagic patches, and red sores. The #1 cause of mortality in koi ponds…

Critical

Freshwater Tropical

Mycobacteriosis (Fish Tuberculosis)

A slow, chronic infection caused by Mycobacterium spp. Symptoms include emaciation, spinal deformity, and granulomas. Zoonotic risk —…

Critical

Koi & Pond

Koi Herpes Virus (KHV)

Notifiable viral disease devastating koi populations worldwide. Mortality 80–100%. No cure — only management and prevention.

Critical

Freshwater Tropical

Velvet (Oodinium)

Dinoflagellate parasite producing a fine, gold-dust coating across the body. More lethal than ich; gill infection causes rapid…

Severe

Freshwater Tropical

Dropsy

Bloated body with pinecone-stuck-out scales — a symptom of organ failure, not a disease itself. Prognosis is generally…

Critical

Freshwater Tropical

Costia (Ichthyobodo)

Parasite (flagellated protozoan) disease of aquarium fish. Key signs: blue-grey film of mucus over skin ('slime disease'), peeling…

Moderate

Freshwater Tropical

Ceratomyxosis

Parasite (myxosporean) disease of aquarium fish. Key signs: distended abdomen, ascites, hemorrhagic enteritis, lethargy, blackened tail, anaemia; chronic…

Critical

Freshwater Tropical

Enteric Septicemia of Catfish (ESC)

Bacterium disease of aquarium fish. Key signs: acute septicaemic: lethargy, head-up vertical floating, petechial hemorrhages on chin and…

Severe

Freshwater Tropical

Furunculosis

Bacterium disease of aquarium fish. Key signs: acute: rapid mortality without obvious external signs; chronic: characteristic 'furuncles' —…

Severe

Goldfish

Spring Viremia of Carp (SVC)

Virus disease of aquarium fish. Key signs: lethargy, darkening, exophthalmia, distended abdomen (dropsy), petechial hemorrhages in skin and…

Critical

Marine / Saltwater

Red Sea Bream Iridoviral Disease (RSIVD)

Virus disease of aquarium fish. Key signs: lethargy, anaemic gills, splenomegaly, enlarged basophilic cells visible histologically in spleen,…

Critical