This school of fish is getting a little bit bigger.

Legendary swimmer Michael Phelps and his wife Nicole Phelps are expecting their fourth child together, they've recently confirmed. In fact, Nicole took advantage of the couple's anniversary to share the big news. 

"A memory from Oct 29 over the last 7 years with you @m_phelps00," she captioned an Oct. 29 Instagram post, which featured seven photos of the couple together. "Happy Anniversary to my best friend, hubby and partner thru life. I couldn't have asked for anyone better!"

Referring to the first image, which shows Nicole with her hand on what looks to be a baby bump as she and Michael pose on the sidelines of a football game, she added, "For those that are wondering… yes! we're expecting our 4th Phelps in 2024."

The littlest Phelps will join older brothers—Boomer, 7, Beckett, 5, and Maverick, 4.

Though they're celebrating seven years of marriage, the 28-time Olympic medalist and his wife have been together for 16 years, having met in 2007. 

And through all that time, they've had each other's backs—especially when it came to supporting Michael's struggles with his mental health. 

"For 15 years, Nicole has seen me go up and down," the athlete told Today in May 2022. "There's no other person that would be able to support me like she has. She's the glue that holds all of us together."

This includes being there when the 38-year-old's mental health shifts, sometimes suddenly. 

"One day I can wake up and I can feel like I'm on top of the world," Michael explained, "and I can do absolutely anything and everything and the next day I can wake up and not want to get out of bed."

The couple also doesn't shy away from being candid with their sons about their dad's struggles with anxiety and depression. 

As Nicole explained, ""I'm very vocal and making sure that the kids are aware that maybe Michael's having a rough day and that [they] didn't do something that made daddy feel this way. It's daddy having his own stuff."

When it comes to her husband, Nicole makes it clear that at the end of the day, she is his no. 1 fan in and out of the pool.

"I keep reminding Michael that I'm not here to judge him," she added. "I'm here to support him. I'm here to love him. I'm not going to shame him. I'm not going to say you can't feel that way. But just making sure I'm there."

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