Begin to investigate. After you are have calmed yourself down, look at the gills, if the fish is not moving then it is not breathing. Betta fish or other labyrinth fish breathe through their mouths, so check the fins for any movement as well.
Tap. If the fish is anywhere near the side of the glass, tap the glass gently. Don't tap too hard or you might shock it which could cause death. If it doesn't respond to the tapping, chances are it is about to die within the next day. You might want to stick the fishnet in the water and try to nudge the fish. Do this very gently as you don't want to hurt your fish, and make sure your skin never comes in contact with the fish.
Shake. Gently twist the bowl a few times back and forth. Alive fish will respond to this movement and move around, even if they had previously been sleeping. If it doesn't respond, the fish may have passed on.
Lift. If the fish doesn't respond to your touch, it is probably on the verge of death. Try lifting its back out of the water for a second. If it doesn't struggle this is a very serious sign that your fish might be dead.
Check for whiteness. If your fish is partially to fully white colored that means it has begun to rot and is dead.
Make sure the fish isn't sick. Sick fish sometimes can look dead. If the fish is in the same position for a long while, and hasn't moved, then the fish is most likely dead.
Your fish may be sleeping. Sometimes, fish stop moving for a while and just sit in one particular location. They are probably just resting. Their colors may also fade while they rest. If your fish are like this when you turn on the lights, don't panic. If you have a goldfish, note that they sleep by "lying down" on the bottom of the tank.Did you just do a water change?
- If so, did you remember to add water conditioner? If not, the chlorine, chloramine, and heavy metals may be affecting your fish. If it is not already dead, or there are other fish in the tank, add water conditioner immediately to curb the effects.
- Also, what temperature is the water? Your replacement water should always be the same temperature as the water you took out. Otherwise, your fish may go into shock from the sudden change. This should wear off soon as the water returns to its normal temperature.