Disease Identification Sheet
Ornamental Fish Disease Guide
Visual reference for 15 common ornamental fish diseases — symptoms, causes and key identification features for rapid on-site diagnosis.
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High Severity
White Spot Disease (Ich)
Ichthyophthirius multifiliis
- Dense white circular spots like salt grains on fins & body
- Fish rubbing against surfaces (flashing behavior)
- Lethargy, rapid gill movement, appetite loss
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High Severity
Fish Lice (Argulus)
Argulus spp. (crustacean ectoparasite)
- Visible flat disc-like parasites clinging to skin
- Red inflammation and irritation patches
- Fish jumping out of water, flashing behavior
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High Severity
Anchor Worm (Lernaea)
Lernaea cyprinacea
- Thread-like worms visibly protruding from skin
- Ulcers and redness at worm attachment sites
- Swollen inflamed skin surrounding anchor point
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Medium Severity
Fin Rot
Aeromonas / Pseudomonas (poor water quality)
- Frayed, torn or progressively disintegrating fins
- Black or brown edges along fin margins
- Fin tissue receding toward body over time
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High Severity
Dropsy
Internal bacterial infection / organ failure
- Severely swollen, balloon-like abdomen
- Scales protruding outward ("pine-cone" appearance)
- Lethargy, loss of appetite, swimming difficulty
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High Severity
Columnaris (Cottonmouth)
Flavobacterium columnare
- White cotton-like patches on mouth and body
- Grey-white lesions spreading rapidly across skin
- Saddle-shaped patch on dorsal area
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High Severity
Red Pest / Hemorrhagic Septicemia
Aeromonas hydrophila / Viral (VHS)
- Red streaks and haemorrhagic bleeding patches on body
- Bleeding at fin bases, abdomen and mouth area
- Ulcers and pop-eye in advanced stages
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Medium Severity
Saprolegniasis (Cotton Mold)
Saprolegnia spp. (water mould)
- White or grey cotton-like fungal tufts on skin
- Often secondary infection appearing over wounds or ulcers
- Growth spreads outward from initial injury site
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High Severity
Branchiomycosis (Gill Rot)
Branchiomyces sanguinis / B. demigrans
- Damaged, patchy and discoloured gills
- Laboured or rapid breathing; fish gasping at surface
- Gills appear marbled or necrotic with pale patches
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Low Severity
Lymphocystis
Lymphocystivirus (iridovirus family)
- Cauliflower-like white or grey nodular growths on fins
- Growths also appear on tail and skin surface
- Rarely fatal; infected fish remain relatively active
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Low Severity
Fish Pox (Carp Pox)
Cyprinid herpesvirus 1 (CyHV-1)
- Smooth, waxy milk-white or pinkish raised lesions
- Wax-candle-like shiny appearance of growth
- Common in carp, koi and goldfish species
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High Severity
Velvet Disease
Oodinium pillularis / O. limneticum
- Fine gold or rust-coloured dust-like coating on skin
- Fish appears "velvety" when viewed in bright light
- Scratching, clamped fins, rapid breathing, weight loss
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Medium Severity
Trichodiniasis
Trichodina spp. (ciliate ectoparasite)
- Excess mucus production on skin and gill surfaces
- Greyish or bluish-white opaque patches on body
- Scratching against objects, restless erratic swimming
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Medium Severity
Swim Bladder Disorder
Infection, overfeeding or physical injury to bladder
- Fish floating upside-down or sideways at surface
- Inability to control depth or maintain normal posture
- Sinking to bottom or trapped helplessly at surface
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Medium Severity
Environmental Stress Disease
Poor water quality, low oxygen, toxic levels
- Fish gasping repeatedly at water surface for oxygen
- No clear external lesions, spots or visible parasites
- Listless behavior, whole group schooling near surface