* Look at the fish's gills. If the gills are white or pale, the fish is likely dead. Healthy gills should be bright red.
* Check the fish's eyes. If the eyes are cloudy or white, the fish is likely dead. Healthy eyes should be clear and black.
* Touch the fish's body. If the fish's body is stiff or rigid, the fish is likely dead. A healthy fish should be flexible and able to move easily.
* Smell the fish. If the fish smells bad, it is likely dead. Healthy fish should have a neutral or slightly sweet smell.
If you think your goldfish is dead, take it out of the tank and check for these signs. If you are unsure whether the fish is dead, you can take it to a pet store or veterinarian for professional evaluation.