It also depends on what sort of food you are feeding and how often you do water changes and gravel cleans.
For example I feed my baby fish 3-4 times a day with live and frozen foods, but I do daily 50% water changes to keep the water clean. I give them as much food as they can eat and then add some live food to the tank. I start with bigger bits of food and the last thing I feed is newly hatched brineshrimp. The brineshrimp swim around the tank until they get eaten. However, this is only for rearing tanks with baby fish in.
My adult fishes that are being conditioned for breeding are fed 2-3 times a day with frozen , live and dry foods and get 50% water changes every couple of days.
Adult fish that aren't being used for breeding only get fed once every couple of days and water changed every week, (most of the fish I have are rainbowfish and dwarf cichlids).
As a general rule most tropical fishes should be fed once or twice a day. In a newly set up aquarium keep the feeding down to once a day and preferably in the morning. Open the curtains or turn the room lights on, leave for 30 minutes and then turn the tank lights on. Leave for another 30 minutes and then offer the fish some food. Fedd them as much food as they can eat in a minute or so. If there is excess food floating around then scoop that out and feed them less next time. If there are catfish and loaches in the tank then it's not quite as important to scoop all the excess food out because the bottom feeders should pick it up.
The idea of turning the lights on for a bit before feeding gives the fish a chance to wake up and they are more likely to eat all the food offered. If you just turn the lights on and drop in some food the fish could still be asleep and the food will be wasted and potentially cause water quality issues.
In an established tank catfish and loaches should be fed at night just after lights out. But the general tropical fish should be fed at least an hour before lights out.
