How often do you feed your fish?
For me depends on the fish. All my juvenile fish are usually fed twice a day. These are all pellet type foods with an occasional treat of a frozen item like brine shrimp or bloodworms. Adult fish usually get just a once a day feeding and many times this includes one day off to purge their system out. My Adult bichir (20" endli, and 18" Ansorgii) I feed only once a week. The juvinile puffer fed once a day but raw type items.
What do you feed them?
Pretty much a pellet diet for all except my puffer who gets, clams, krill, worms and the bichir that get tilapia soaked in Boyds vitamins.
And lastly, what is your reasoning for these answers?
For me the fish that I seem to really see way overfed has to be adult bichir. My fish are wild caught and they way I feed them, they look lean and elongated like they look in pictures of wild caught fish. I could feed them nightly but then they would look like giant stuffed sausages, lol.