SEA LIFE Sydney Aquarium has announced their same-sex penguin couple, Sphen and Magic, have 'fostered' another egg this season.

Tish Hannan, Penguin Supervisor at SEA LIFE, says the "power couple" has been inseparable since the beginning of 2018.

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Last October, keepers gave the two males a 'fostered' egg to incubate together until it hatched.

Their first 'offspring', Baby Sphengic, has just turned one.

Keepers say they didn’t hesitate to give the penguins another egg to 'foster' this year after they noticed one of the other penguin couples struggling to incubate two eggs at the same time.

Like last year, the male penguins will together incubate the egg until it hatches - a process that can take up to 68 days.

“We had no doubt that they would couple up again this year and build an impressive nest," Hannan said.

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Aquarium staff are excited Sphengic may have a little brother or sister on the way, although they're yet to confirm if the egg is fertile.

Hannan said the loyal and protective duo are fantastic parents who gave Sphengic an "excellent start to life under their care".

"While she’s still a bundle of energy and very loud, she’s matured nicely."