Mouthbrooding

Mouthbrooding is a form of parental care in which a fish parent holds eggs or newly hatched fry in its mouth for incubation and protection. The strategy occurs in several families, but it is especially common among cichlids, and it also appears in some gobies, cardinalfish, and other groups. Mouthbrooding can involve only one parent or both parents, depending on the species and mating system.

In species with maternal mouthbrooding, the female retrieves fertilized eggs or fry into her buccal cavity, where they are protected and exposed to a more stable environment. Paternal mouthbrooding is observed in a few species, and some lineages exhibit biparental mouthbrooding, where parents alternate incubation duties. Incubation lasts roughly from one to several weeks, again varying by species. During this period, the eggs hatch into free-swimming fry that may remain in the mouth for additional days or weeks before being released. While in the mouth, fry rely on the parent’s protection, and feeding is typically limited or suspended.

The strategy offers protection from predators and environmental hazards, but it imposes costs on the incubating parent, notably reduced ability to feed and potential growth delays. Mouthbrooding also requires behavioral and morphological adaptations, such as a buccal cavity capable of accommodating developing offspring and regulating temperature or humidity within the mouth. After release, fry begin independent feeding and dispersal, contributing to the species’ reproductive success in certain ecological contexts.

Mouthbrooding has been widely studied as a key example of diverse parental care strategies in teleost fish, particularly among African cichlids, where it contributes to patterns of diversification and life-history evolution.