Species belonging to the Oreochromis genus typically care for their young through mouthbrooding, oral incubation of the eggs and larvae. Similar to other tilapia, Nile tilapia are maternal mouthbrooders and extensive care is therefore provided almost exclusively by the female. After spawning in a nest made by a male, the young fry or eggs are carried in the mouth of the mother for a period of 12 days. Sometimes, the mother will push the young back into her mouth if she believes they are not ready for the outside. Nile tilapias also demonstrate parental care in times of danger. When approached by a danger, the young often swim back into the protection of their mother’s mouth.[5] However, mouthbrooding leads to significant metabolic modifications for the parents, usually the mother, as reflected by fluctuations in body weight and low fitness. Thus, parental-offspring conflict can be observed through the costs and benefits of mouthbrooding. On one hand, protection of the young ensures passage of an individual’s genes into the future generations; however, caring for the young also reduces an individual’s own reproductive fitness.[10]
As stated in the reproduction section, female Nile tilapia exhibiting parental care show extended interspawning periods. One of the benefits of this extension results in slowing down vitellogenesis (yolk deposition) to increase the survival rate of one’s own young. The size of spawned eggs correlates directly with advantages concerning hatching time, growth, survival, and onset of feeding since increased egg size means increased nutrients for the developing young. Thus, one of the reasons behind a delayed interspawning period by female Nile tilapia may be for the benefit of offspring survival.[11][13]
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