I feed them 3 times a day: 'Breakfast flakes' in the morning, a few tubifex in the afternoon, and our ritual bloodworms( for the fish) and brandy(us) before bed. Our Bichir, named 'Bonk', gets a krill or a mosquito fish once.
You know, it really does depend on the fish, little nibblers like mandarin gobies and seahorses need constant feeding, fish like marbled gobies will eat every few minutes if you let them but only need a good meal every couple days.