Interactive Fish Disease Symptom Checker (3-Click Diagnosis)
Identify aquarium fish parasites, bacterial infections, fungal growths, and water-toxicity emergencies in 3 clicks—with critical temperature rules and first-2-hour rescue protocols.
1. Where is the primary symptom located?
Step 1 of 3 · Location2. What specifically do you observe?
Step 2 of 3 · Visual SignFrequently Asked Questions About Fish Disease Diagnosis
- How do I tell the difference between Ich (white spot), Velvet (Oodinium), and Columnaris?
- Ich looks like distinct, raised grains of table salt (0.5–1 mm) scattered across fins and body. Velvet (Oodinium) looks like ultra-fine golden-yellow or rust dust best seen by shining a flashlight on the fish in a darkened room. Columnaris forms flat, grayish-white cottony patches around the mouth or a saddleback lesion across the dorsal fin and kills rapidly if you raise the water temperature.
- Why is raising water temperature dangerous when diagnosing white patches on fish?
- While heat (28–30°C / 82–86°F) speeds up the life cycle of Ich parasites, it causes Flavobacterium columnare (Columnaris / Cotton Mouth) to multiply exponentially and lowers dissolved oxygen, often killing the fish within 24 hours. Never raise temperature unless you are 100% certain the spots are distinct salt-grain Ich cysts.
- What should I do first if my fish are gasping at the surface or lying on the bottom?
- Before adding any medication, test water parameters (Ammonia NH3 and Nitrite NO2) and maximize surface aeration with an air stone. Over 60% of sudden fish emergencies are caused by ammonia or nitrite spikes, chlorine exposure, or oxygen depletion rather than infectious pathogens.