Free tools
Start with a symptom, a body area, a water reading, a dilution target, or a printable decision path. Each tool is free and keeps the values you enter in your browser.
Visible signs and behavior
Choose what you can see, add tank context, and get a cautious list of possible causes, urgency signals, and next checks.
Water-quality triage
Review ammonia, nitrite, nitrate, pH, temperature, and fish behavior for possible water-quality warning signals.
Volume and water changes
Estimate usable water volume after the waterline, substrate, and decor displacement, in liters and US gallons.
Dilution and target planning
Estimate how one or repeated water changes affect nitrate, nitrite, ammonia, salinity, or another dissolved measurement.
Explore by body area
Select the eyes, mouth, gills, skin, belly, fins, or behavior to find the most relevant symptom and disease guides.
Print or save as PDF
Use a symptom-first decision chart for breathing problems, spots, fin damage, swelling, eye changes, and unusual behavior.
How they work
The tools use local, deterministic rules and calculations. They do not upload the values you enter or turn a broad fish-health pattern into a certain diagnosis.
01
Visible signs, behavior, spread, and recent tank events decide which checks deserve attention first.
02
A blank or untested reading stays unknown. The tools never silently interpret missing information as zero.
03
Results link to relevant guides and the mobile photo scanner, while keeping water and urgency in view.
Fish Disease Identifier
Scan a photo in Fish Disease Identifier and get likely disease matches, possible causes, and next steps to consider.
Educational only. Not veterinary advice.
