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
Brackish Water 2 Freshwater Tropical 46 Goldfish 29 Koi 4 Koi & Pond 24 Marine / Saltwater 13
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
Severity
Critical 20 Mild 2 Mild To To To Severe 1 Moderate 22 Moderate To To To Severe 2 Severe 9

12 conditions

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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

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

Mycobacteriosis (Fish Tuberculosis)

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

Critical

Freshwater Tropical

Hexamita (Hole-in-the-Head)

Intestinal flagellate parasite causing pitted lesions on the head and lateral line, especially in cichlids and discus. Often…

Moderate

Freshwater Tropical

Cloudy Eye

Hazy or opaque film over one or both eyes — usually a sign of bacterial infection or chronic…

Moderate

Freshwater Tropical

Hole-in-the-Head Disease (Hexamita)

Parasite (flagellated protozoan) disease of aquarium fish. Key signs: pinhole-sized pits on head that enlarge into cavities; lesions…

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

Goldfish

Asian Tapeworm Infection

Parasite (cestode) disease of aquarium fish. Key signs: heavy intestinal worm burden, emaciation, distended abdomen, anaemia, intestinal blockage;…

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