Kosher sushi question

My husband is Sephardi, but didn’t grow up keeping kosher. We were talking about sushi, as I’d recently been to a new place with my sister, and he was asking if eating roe is kosher. I thought yes if it’s from a kosher fish, like salmon roe, but then he asked how that’s not breaking the whole milk and meat rule because he’s heard the phrase “you shouldn’t cook a baby in its mother’s milk.” Does the question make sense? 🙃🙃