Disease & Trouble Encyclopedia
Comprehensive guide to common diseases and troubles in marine fish, coral, reptiles, and tropical fish. Early detection is key.
Want to quickly identify a disease from symptoms? Use our Find by symptom. Browse common symptoms to find related conditions.
Marine Fish Diseases
Marine Ich (Cryptocaryon)
Symptoms
White spots on body. Rubbing against surfaces. Rapid breathing.
Cause
Cryptocaryon irritans parasite. Often triggered by temperature drops or stress.
Trichodina
Symptoms
Cloudy body surface, excess mucus. Clamped fins. Loss of appetite.
Cause
Trichodina ciliate parasite. Often caused by poor water quality or overcrowding.
Velvet Disease (Amyloodinium)
Symptoms
Gold to brown dust-like coating on body. Breathing difficulty. Rapidly worsening.
Cause
Amyloodinium ocellatum dinoflagellate. Progresses faster than ich with higher mortality.
Lymphocystis
Symptoms
White cauliflower-like growths on fins and body. Appetite usually maintained.
Cause
Viral infection. Triggered by stress or poor water quality. No direct cure; often self-resolves via immune response.
Vibriosis
Symptoms
Red spots and ulcers on body. Pop-eye. Rapid deterioration.
Cause
Vibrio bacteria infection. Often enters through wounds. Risk increases with poor water quality.
Coral Troubles
Coral Bleaching
Symptoms
Coral loses color and turns white. Polyp extension decreases.
Cause
High temperature, excessive light, sudden water quality changes. Loss of symbiotic zooxanthellae.
Rapid Tissue Necrosis (RTN)
Symptoms
Tissue peels off rapidly within hours to days. White skeleton exposed.
Cause
Primarily bacterial infection. Triggered by water quality swings, introduction stress, or poor flow.
Slow Tissue Necrosis (STN)
Symptoms
Tissue recedes more slowly than RTN. Bleaching spreads gradually from the base.
Cause
Chronic issues: nutrient buildup, insufficient light, low alkalinity.
Brown Jelly Disease
Symptoms
Brown jelly-like substance on coral surface. Spreads rapidly to nearby corals.
Cause
Protozoan infection. More common on damaged or weakened coral.
Flatworm Infestation
Symptoms
Small brown worms cover coral surface. Reduced polyp extension. Color loss.
Cause
Flatworm parasites. Usually introduced with new coral. Preventable with dipping.
Reptile Diseases
Retained Shed (Dysecdysis)
Symptoms
Old skin remains on toes, tail tip, around eyes. Can cause necrosis from poor circulation in severe cases.
Cause
Primarily insufficient humidity. Also poor nutrition, dehydration, or lack of rough surfaces in enclosure.
Metabolic Bone Disease (MBD)
Symptoms
Jaw deformity, limb tremors, fractures. Severe cases cause difficulty walking.
Cause
Calcium deficiency, vitamin D3 deficiency, insufficient UV-B. Especially common in growing juveniles.
Respiratory Infection (RI)
Symptoms
Open-mouth breathing, nasal discharge or mouth bubbles, loss of appetite, lethargy.
Cause
Keeping at too-low temperatures, sudden temperature changes, unsanitary conditions. Bacterial or fungal infection.
Mouth Rot (Stomatitis)
Symptoms
Swelling and redness around mouth. Cheesy pus inside mouth. Appetite loss. Unable to close mouth.
Cause
Bacterial infection. Often secondary to injuries (glass collision). Weakened immunity contributes.
Parasitic Infection
Symptoms
Weight loss, diarrhea, losing weight despite eating. Worms may be visible in feces.
Cause
Internal parasites (nematodes, tapeworms) or coccidia. More common in wild-caught specimens.
Tropical Fish Diseases
Aeromonas Infection
Symptoms
Red hemorrhaging on body, raised scales (dropsy), bloating. Pop-eye.
Cause
Aeromonas bacteria. Always present but manifests with poor water quality or stress. Also damages internal organs.
Columnaris Disease
Symptoms
White cotton-like patches on mouth, fins, body. Fin erosion. Whitened mouth.
Cause
Columnaris bacteria. More active at higher temperatures. Risk increases above 25C.
Freshwater Ich (Ichthyophthirius)
Symptoms
Multiple white spots on body and fins. Rubbing against objects. Appetite loss.
Cause
Ichthyophthirius multifiliis ciliate. Triggered by temperature drops or introducing new fish.
Fungal Infection (Saprolegnia)
Symptoms
White fuzzy mold on body and fins. Common around wound sites.
Cause
Saprolegnia fungal infection. Usually secondary to wounds. More common at low temperatures.
Fin Rot
Symptoms
Fin edges turn white and dissolve. Progresses toward the fin base.
Cause
Bacterial infection (Aeromonas, Columnaris). Caused by poor water quality, overcrowding, or stress.
Disclaimer
This information is for general reference only. Always consult a veterinarian or specialist for actual diagnosis and treatment. If symptoms are observed, seek professional veterinary care as soon as possible.