An uncommon visitor turned up in Edgartown harbor this weekend: a juvenile African pompano, an iridescent tropical fish that likely drifted north from waters off the southern United States.

The sighting was reported this weekend by longtime squid fisherman Janet Messineo, who spotted the fish swimming in Edgartown harbor before it was caught. What she thought was a weed sped off through the harbor.

Later, she got a better look at what she describes as “a beautiful tropical-looking fish with tendrils.” It was her first encounter with the species.

Ms. Messineo was there at around 10 p.m. Saturday when a local squid fisherman caught a squid on a jig. As the squid was being pulled onto Memorial Dock, it grabbed the African pompano.

After the squid and the fish were on the dock, Ms. Messineo held the juvenile fish briefly in her hand before letting it go.

“The squid grabbed the little fish, so I ran over and I was able to put the fish in my hand to just get a closer look at it,” Ms. Messineo said. “And then I just threw it back in the water. But it stayed around. It flapped around on the top of the water for a while.”

“It was so beautiful,” she added. “I wanted to keep it, but I couldn’t think of any rational idea why I should kill this fish, so I threw it back.”

Greg Skomal, senior marine fisheries biologist at the Division of Marine Fisheries, confirmed the catch Monday morning based on an email from Ms. Messineo. He told the Gazette that the species was rare but not unheard of in local waters. “It's not something we see a lot of, but scientists had documented it going back to the ’30s,” he said.

The African pompano is a tall, narrow fish usually silvery blue or green in color. It typically has long, wispy dorsal and anal fins that are thought to confuse predators. It inhabits tropical waters worldwide and is often found off the coast of the southern United States. The one caught this weekend was about six inches long, but adults can grow to more than 50 inches long.

“In my years of fishing, we are getting more and more tropical fish,” Ms. Messineo said. “Edgartown harbor seems to be one of the places that some of these strange fish seem to show up from time to time.” She said she though the increase could mostly be attributed to changing weather conditions and higher water temperatures.

Mr. Skomal said the fish likely wandered north this summer. He said it could have been feeding on sand eels, silversides or small herrings that live around the Vineyard.