I do believe that it will be in a stage of rigamortis and will soon start to go solid. If left for more than three hours there is no chance of reincarnation. If however you lick its left eye within three hours of rigamortis then it shall come back to life.
they just settle at the bottom of fish tank
gravel
A fish sinks to the bottom of the tank because its body is denser than the water, causing it to be pulled down by gravity.
I suggest that you learn more about your fish in your aquarium. One of your fish might be a bottom sucker which means that they eat all of the dirt on the side or bottom of your tank. If one of your fish are bottom suckers, that's probably the reason why your aquarium is clean. If none of your fish are bottom suckers, than somebody must be secretly cleaning your tank for you.
If your fish food is staying afloat for a week it is most likely because it is just buoyant and you have overfed your fish. Feeding your fish less will reduce fish food staying afloat as well as help keep your fish and tank healthy.
It dies
Certain types of fish, such as catfish and plecos, are known for cleaning the bottom of a tank by consuming algae and leftover food.
Fish eggs, fish sperm, mold.
food flaots
You simply take any fish and drag it to the bottom of the tank and then drag it up (fastly) and it will go soaring!
ummm your fish is dead....sorry.......
Could be anywhere.