Goldfish
Fungal Diseases in Koi & Goldfish
Fungal diseases — most commonly caused by water moulds of the genus Saprolegnia — are a frequent secondary…
Moderate
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
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
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
Fin Rot
Progressive deterioration of fin tissue caused by opportunistic bacteria — usually a symptom of poor water quality.
Mild
Freshwater Tropical
Swim Bladder Disorder
Loss of buoyancy control — fish floats, sinks, or swims at odd angles. Common in fancy goldfish and…
Moderate
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
Trichodina Infestation
Parasite (ciliate protozoan) disease of aquarium fish. Key signs: excessive mucus (slime coat), pale or 'milky' patches on…
Moderate
Freshwater Tropical
Gill and Skin Flukes (Dactylogyrus & Gyrodactylus)
Parasite (monogenean flatworm) disease of aquarium fish. Key signs: increased mucus on gills/skin, flashing, gasping at surface, frayed…
Moderate
Brackish Water
Marine Velvet (Amyloodinium)
Parasite (dinoflagellate) disease of aquarium fish. Key signs: dusty gold-brown coating on skin and gills, rapid respiration, gasping…
Moderate
Marine / Saltwater
Marine Ich (Cryptocaryon irritans)
Parasite (ciliate protozoan) disease of aquarium fish. Key signs: white spots (larger and more diffuse than freshwater ich),…
Moderate
Freshwater Tropical
Columnaris (Cotton-Wool Disease)
Bacterium disease of aquarium fish. Key signs: white-grey saddle-shaped lesion across back, frayed fins, mouth fungus-like white patches,…
Severe