Fish are animals that they don't ask for food And, if you do not look at the aquarium, after getting used to seeing it as something else in the house, the day may come when you forget to feed the fish and you don't know if it is good or bad.
To tell the truth, not giving them a day or two to eat is not really bad because the fish hold out (although you have to be careful because they can attack each other if they are hungry and end up losing some). However, perhaps feeding the fish is something that you should not follow a strict schedule.
Fish usually eat at different times of the day. There are those who give them food several times (learn here how to prepare homemade fish food) but others throw it only once a day because they know that the food stays on the ground and then they eat it little by little.
To remember when to feed it, the best thing to do is place that activity in something you do every day. For example, before you go to work, or after school, if the children are the ones who feed the fish. Doing it day by day becomes a habit and it is easier to remember to feed them.
What time is the best?
To tell the truth there is no precise time although from my experience I will tell you that, at night, they don't usually eat much and less if there is no light. They prefer to wait for the next morning to eat rather than at night.
First thing in the morning (in the morning) they tend to eat faster (and thus make the water less dirty). I would recommend at that time to avoid eating food for a long time in the water (some fish do not like it).