Now that I met your family, I want you to meet mine.
A joke about a man dating a fish. When couples date for a while, they often meet each-other's families. Here, the caption implies that the fish/man couple just met the fish's family in the ocean, and are perhaps on the way to meet the man's family on land. It's funny because it's a surprising framing of why a man and a fish might be leaving the water together.