Fish that keep their young in their mouths sometimes eat them

The person is Christa Lesté-Lasserre.

The fish that protect their offspring by keeping them in their mouths aren't the models of parental devotion. Some of the stress of parenting may be alleviated by the fact that they commonly eat up to half of their children.

The two weeks in which female Astatotilapia burtoni fish keep their eggs and hatchlings in their mouths leads to weight loss, reduced immunity, faster aging and lower chances of reproduction again. Peter Dijkstra at Central Michigan University says that by consuming up to half their brood, the mother fish get the nutrition they need to survive.

He says that the females are gaining something from it that could potentially boost their health.

After laying eggs and keeping offspring in their mouths, A. burtoni mothers have higher levels of oxidative stress. The number of baby fish in the mothers mouths dropped over the course of two weeks, with up to 60 percent of the young disappearing.

The researchers observed 31 mouth-brooding female A. burtoni fish and removed their eggs.

The mouths-brooding females had fewer hatchlings by the end of the study period than they had at the beginning. There was a variation in the number of missing fry.

The mothers kept their mouths closed and I never saw them drop them. The only plausible explanation was that they were consuming some of them.

Read more: The male fish who eat their eggs because they want better babies

The researchers took blood and liver samples from mother fish two days, six days and two weeks after they were born. At the two-day mark, they found that females who had their eggs removed had more damage to their genes than females who hadn't.

There wasn't much difference between the brooding and non-brooding females over the course of a couple of weeks. The more young the mother is, the higher the levels of anti-oxidants are in her body. The mothers were sacrificing their children to boost their own health and reduce the stress on their bodies caused by the parenting burden.

It would be beneficial to eat some of those young and be able to reproduce again in the future, rather than die after that reproductive cycle and only have produced X number of young. It's more of an investment in the future.

The journal is titled Biology Letters.

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