Quarantine New Fish
Quarantine gives new fish time to recover from shipping stress and show problems before they reach the display tank.
Observation, diagnosis, and treatment are different
Use this page to organize observations and first checks. Do not treat from one symptom alone; water-quality stress, injury, parasites, bacterial disease, and handling stress can overlap.
First checks
Check temperature, ammonia, nitrite, nitrate, pH, breathing, appetite, flashing, spots, fins, and stool. Watch longer if anything looks off.
Often confused with
Acclimation, hospital tanks, prophylactic medication, and normal hiding after transport.
What to do now
Observe first, keep water stable, avoid automatic medication unless there is a clear reason, and never rush a visibly stressed fish into the main tank.
Safety note
This is triage, not diagnosis. Test water before treating, avoid mixing medications, and check species sensitivity for scaleless fish, fry, shrimp, snails, and other inverts.
Next safety steps
Before dosing, read aquarium medication safety. If one fish needs closer observation, use the hospital tank guide. For new arrivals, start with quarantine new fish.