In nature, fish devour whenever they are hungry and their food is available. Fish are very opportunistic and will eat whenever they get a chance. If food sources are plentiful, fish will eat numerous times a day. In contrast, if food sources are scarce, fish might go for days between meals. It means if you offer food to fish, they will usually gobble it up even if they are not starving. No matter how frequently fish are fed, they will react to food as if they have not had anything for days.
If your fish aquarium is new, you should feed only once a day, and learn to feed carefully. The more wastes that are produced by the fish, the more chance that they will experience elevated ammonia and nitrite levels in the water which can kill them. Once your aquarium gets older and the nitrogen Cycle is established, you may feed a couple of times a day.
Frequency of feeding also varies on the type of fish. Generally, most fish do well on one feeding per day. If you want to feed two times a day, you should keep the food amount very small. Furthermore, the timings are not critical with the exception of some nocturnal feeders such as certain catfish. If you have nocturnal fish in your tank, make sure to feed these fish just prior to turning the lights out at night.
There are some exceptions to the feeding rule of ‘once per day’. Herbivores fish need to eat frequently, as they don’t have large stomachs to hold lots of food. In nature, these fish would graze all day long on the plants. Therefore, they should be given several small feedings per day, or provided with live plants they can nibble. In addition to this, newly hatched fry and young fish, require more frequent feedings of special foods designed for them.
Final Words:
For all situations other than herbivorous fish and young fish, you should feed once a day. A good thumb rule is to feed no more than the fish consume completely in less than the 5 minutes. If you have a doubt, underfeed your fish. If you over feed your fish, the uneaten food will produce toxic by-products which can be harmful to the fish. In the event you do overfeed, try to remove the uneaten food promptly using a siphon or net.