Even when there is an ample supply of food, guppies may still eat small fish. Although guppies might reduce their behavior of eating small fish when food is plentiful, it's not an absolute certainty. Guppies have no consciousness; they simply decide whether to eat based on the availability of food. Small fish are a source of nutrition for them, so they may devour the small fish.
Moreover, guppies don't have a distinct sense of fullness. They will keep eating until they physically can't eat any more. Therefore, even with sufficient food, guppies may still eat small fish due to hunger. To avoid this situation, it is recommended to keep adult guppies and newly born small fish separately to ensure the safety of the small fish.
To ensure the health of guppies and prevent them from eating small fish, the following measures can be taken:
Separate Rearing: Immediately separate the guppies from the small fish after they give birth, and put them back together to be reared when the small fish have grown up.
Use Isolation Devices: A funnel-shaped device can be used to isolate the female fish on top while the small fish are at the bottom, so that the female fish won't be able to eat the small fish.
Control the Feeding Amount: Although guppies don't have a distinct sense of fullness, the possibility of them eating small fish can be reduced by controlling the feeding amount.
Through these measures, the small fish can be effectively protected from being harmed by adult guppies.