When fish die do they float or sink?
Most fish are slightly denser than water, so sink immediately after death. However, like a drowned human, they become more buoyant over time as bacterial decomposition produces gases inside the body. Usually, enough gas builds up in body cavities to make the corpse float, like an inflated balloon.
How do you know when fish will die?
Last but not least, a key sign of death is when the gill flaps or operculum stop moving. The gills are what keep the fish alive by providing oxygen and removing carbon dioxide from its system, so many hobbyists turn to the gills to observe for signs of life.
Why is my fish not moving?
Listlessness: If your fish seem tired and lethargic, it can be as a result of many factors. One common cause is improper water temperature. If your fish’s water is too hot or too cold, they will be very inactive. Check your heater and verify that your aquarium is at the right level.