5 minute read · September 27, 2026
Why are my fish dying and what to do in the next hour
Sudden fish losses almost always trace to water quality, temperature or disease. Here is how to tell which, what to stop doing immediately, and when to call for help in Palm Beach County.
Stop first
Stop feeding. Do not add any chemical, medication or new water until you know what is wrong. Most tanks are made worse in the first hour by well-meant fixes.
Check the three things
Temperature: a failed heater or a chiller that quit in August will kill fast. Oxygen: fish gasping at the surface means a pump or air problem. Water: test ammonia, nitrite and, on a reef, salinity and alkalinity. A single number out of range usually tells the story.
Try it on your tank
Look at the fish
Spots, clamped fins, rapid breathing, hiding, or one species affected and not others point to disease or aggression rather than water. Take a photo. It will help whoever you call.
Then call
If more than one fish is affected or you cannot find the cause, call Jason with the photo and the test results. He has talked people through this on the phone before, and if the tank needs someone standing in front of it, he will come out.
The short version
Stop feeding, check temperature, oxygen and water, photograph the fish, then call.