Use a tabo...
Toilet tank
You usually depress a handle on the tank.
because there is a Dukie stuck in the bottom of the toilet so you have to take out your toilet and flush the system.
Nothing it goes into a holding tank
remove immediately from the tank using a net and if the fish is small, flush it down the toilet, otherwise bury it deep in the ground.
Each flush of a toilet uses the same amount of water.
not all toilet bowls and tanks are compatible. If your toilet bowl has no holes for a tank it most likely a bowl that is made for a flush valve, or a high or low boy mounted tank.
about 1.3 gallons per flush
Certainly, as long as, all the solids are removed during the flush.
If your water comes from a well and you have your own pump and tank. The tank may be waterlogged.
It's the Rubber seal at the bottom of your water tank, when you flush the rubber seal raises and the water flashes your toilet. Generally its black but not always.
The internal trap is partially or fully blocked