The general recommendation is to feed the fish in the aquarium twice a day. However, there are a few things to consider:

1. Types of fish
Active fish: Fish like guapi and neon tetra can feed twice a day.
Slow fish: Fish like cichlids may prefer to eat once a day, to avoid competition with other fish.
2. The amount of food
Dry food: try to feed an amount that can be eaten within 2-3 minutes. Avoid food scraps to prevent water contamination.
Frozen or live food: If you feed the fish frozen or live food, be sure to give a smaller amount than usual, as this food may be more concentrated.

3. Indications for the need for feeding
Fish behavior: If the fish look hungry, it can be a sign that you can feed them more.
Illness or stress: If the fish are stressed or have health problems, you may want to reduce the frequency of feeding until they recover.
4. Fasting days
One day a week: you should consider setting one fasting day a week, when you don't feed the fish. This may help keep them healthy and prevent digestive problems.

5. Glimpse of fish behavior
Hungry or full: see how the fish react while feeding. If they eat very quickly, the food may not be enough. If they are not interested, maybe the quantity should be reduced or the quality of the food should be checked.
Behavioral changes: Any changes in behavior such as lack of appetite or fatigue may indicate health problems that may be related to food.
Summary
Proper feeding of fish in the aquarium is a significant part of their care. It is important to understand the specific needs of each type of fish and make sure you provide them with appropriate and high-quality food. A commitment to proper feeding and maintaining water quality will help you ensure that your fish are healthy and happy.