Why are your guppies not eating?

Answer 1

The most common cause for fish to go off their food is bad water. The next most common is bad or wrong parameters for the species. Try doing a few large water changes and check that its pH and temperature are OK and the filter is working properly.

Some female Cichlids particularly African Rift lake Cichlids are maternal mouth brooders. This means that they carry their fertilized eggs and eventually the fry in their mouths until they hatch and the mother can't keep them in her mouth any longer due to space. look for a bulge in the chin area and as she breathes you might be able to catch a peek of the eggs or fry in her mouth when she opens it.

Answer 2

They might be tired of the food they eat. Maybe try giving them a treat every once and a while, like some bloodworms.

Answer 3

She might be sick. The water may be too cold or the chemicals are off. Or perhaps she just doesn't like that type of food and you should try another.