how much do you give the fish, like how often do you feed it to them? how long would you say to leave it in the tank... ...one day and take it out before it starts to decades? and is it health for them?
Don't leave it in the tank for longer than a day, whatever you do decide to use. Amounts are kind of up to you and the fish. It's better that they eat it all rather than leaving a whole bunch to just spoil in the tank.