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
Disease library
Fish disease library
Every disease, parasite, and infection in our knowledge base. Tap the keywords to narrow the list — the page updates with a clean, shareable URL.
Fish type
Symptom
Bloated Abdomen 2
Bloated belly 2
Clamped Fins 3
Cloudy Eye 1
Color Fading 1
Cotton Like Growth 1
Cottony Tufts 2
Darkened color 4
Dropsy 1
Emaciation 4
Erratic Swimming 7
Excess Mucus 3
Eye Discharge 1
Fin Erosion 1
Fin Rot 3
Fin Whitening 1
Flashing 4
Flashing / rubbing 8
Floating 1
Frayed Fins 6
Gasping at surface 4
Gill Damage 1
Gold Dust Coating 1
Gold-dust film 1
Granulomas / nodules 3
Head Pitting 1
Hemorrhage 1
Hemorrhaging 13
Lateral Line Erosion 1
Lethargy 19
Listless near bottom 1
Loss Of Appetite 7
Loss Of Balance 1
Mouth Erosion 1
Open Sores 4
Pale Gills 4
Pinecone Scales 1
Pop Eye 17
Rapid breathing 4
Rapid Gilling 4
Red Fin Bases 1
Red Ulcers 2
Scale Loss 1
Scratching 3
Sinking 1
Skin Erosion 1
Skin lesions 4
Spinal Deformity 2
Sudden death 3
Sunken Eyes 1
Swimming Sideways 1
Tissue necrosis 8
Ulcers 1
Visible parasite 1
Wart-like growths 2
White Fin Edges 1
White Grey Patches 1
White Patches 1
White Patches Gills 1
White Spots 5
White Stringy Feces 1
White Tail 1
Cause
Aeromonas hydrophila 1
Aphanomyces spp. 1
Argulus spp. 1
Bacteria 16
Branchiomyces spp. 1
Columnaris 1
Dactylogyrus spp. 1
Environmental 2
Fungus 3
Ichthyophthirius multifiliis 1
Lernaea spp. 1
microsporidian 1
Parasite 18
Pleistophora hyphessobryconis 1
Pseudoloma neurophilia 1
Pseudomonas fluorescens 1
Saprolegnia spp. 1
Trichodina spp. 1
Virus 14
Marine / Saltwater
Marine Ich (Cryptocaryon irritans)
Saltwater white-spot disease. A 2006 resistant strain renders traditional copper and formalin treatments ineffective — quinine sulfate is…
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
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
Freshwater Ich (White Spot Disease)
The most common freshwater fish disease. Tiny white spots resembling grains of salt cover the body and fins.
Moderate
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
Mycobacteriosis (Fish Tuberculosis)
A slow, chronic infection caused by Mycobacterium spp. Symptoms include emaciation, spinal deformity, and granulomas. Zoonotic risk —…
Critical
Freshwater Tropical
Branchiomycosis (Gill Rot)
Fungus (true fungus) disease of aquarium fish. Key signs: rapid breathing, gasping at surface, gill necrosis with white/marbled…
Severe
Freshwater Tropical
Streptococcosis
Bacterium disease of aquarium fish. Key signs: exophthalmia (often unilateral, 'pop-eye'), corneal opacity, spinning/spiral swimming, darkening, hemorrhages around…
Severe
Freshwater Tropical
Fin and Tail Rot
Bacterium (mixed/opportunistic) disease of aquarium fish. Key signs: ragged, frayed or eroded fin edges; white margins followed by…
Moderate
Freshwater Tropical
Motile Aeromonad Septicemia (Ulcer Disease)
Bacterium disease of aquarium fish. Key signs: open red ulcers (especially in koi), hemorrhagic skin patches, distended abdomen…
Moderate
Freshwater Tropical
Ceratomyxosis
Parasite (myxosporean) disease of aquarium fish. Key signs: distended abdomen, ascites, hemorrhagic enteritis, lethargy, blackened tail, anaemia; chronic…
Critical