Only begin to feed after 24 hours.
Feeding is a very important process that must be carefully distributed every day, preferably by the same person and in very small quantities.
The rule is to give a pinch of food (flakes or granules) once or twice a day, knowing that all should have disappeared within one minute after feeding. Excess food is a major problem in this sort of environment that can lead to pollution and the build up of nasty bacteria, as well as raising the mortality rate in aquariums.
Daphnia food (ref. 361 320)