the offspring of a female to make that female more sexually receptive or to re-mate. By doing this, a male might be able to prolong its lifetime mating opportunities. Female fish may compete for mating opportunities with males by raiding the male's nest and eating the eggs inside. Females may also use cannibalism – particularly birds and bees that live in a joint-nesting social structure – as a way to establish reproductive dominance by eating the eggs of a co-breeder. In some animal cultures, competition may lead to instances of egg thievery, nest takeovers, and cuckoldry. However, the consumption of an animal's brood is often more beneficial than the consumption of unrelated conspecifics, since it takes less energy to eat their own offspring and lessens the chance of getting their own brood raided when getting food while away from their offspring. Filial cannibalism in fish Many species of fish with paternal care will exhibit total clutch cannibalism or partial clutch cannibalism. This is likely in order to gain additional energy and nutrients, which could ultimately benefit their future reproductive success. Cannibalized offspring can act as a food source for the male fish guarding them. Often, male fish will consume their entire clutch if it is too small, as the energetic costs of caring for a small clutch may be greater than their reproductive benefits. In other fish, filial cannibalism has been observed to regulate male fish's endocrine systems. For example, in the blenniid fish Rhabdoblennius nitidus, males have an androgen-dependent brood cycle. However, the acquisition of eggs suppresses the secretion of androgen, preventing males from performing courtship displays and obtaining more offspring. As a result, R. nitidus males will cannibalize all their eggs when the clutch size is small, so they can reproduce and care for a larger clutch of eggs (and subsequently have more offspring). In some cases, the size of the clutch seems to determine whether the male consumes the entire clutch or only part of it. For example, in the fantail darter, males seem to consume a fixed number of eggs regardless of clutch size, which may be in order to cover the energy costs of guarding the eggs. Since the cost of parental care does not increase significantly with a larger clutch size, having small clutch size may not be worth amount of care invested in it. This is further compounded by the fact that in