Is the Aquarium Trade to Blame?

A lionfish juvenile roams its aquarium after being collected off Long Island, New York. Click on image for larger view and further details.

The aquarium trade appears the most likely vector for the introduction of lionfish into U.S. waters, but the lionfish's introduction into the Atlantic remains something of a mystery. Recent research indicates that a number of other tropical aquarium fish are currently surviving off the coast of Florida. Also, the color patterns of lionfish sighted off the Atlantic coast of the U.S. are similar to those from the Philippines, where many lionfish are collected for the aquarium trade.

Scientists say it is impossible to determine if the lionfish released in 1992 account for the species invasion of Atlantic Ocean. Some scientists have suggested that lionfish entered Atlantic waters when larvae or juvenile fish were trapped in ships moving from the Pacific to the Atlantic and were released when the ballast water was pumped out.

An adult lionfish on display in a home aquarium. (Photo credit: Hiroshima University, Graduate School of Biosphere Science)

However, there is no evidence to support ballast water as the source for the lionfish invasion, although it is a common source of aquatic alien species introductions generally. Further, although lionfish have been introduced into the western Mediterranean, probably through the Suez Canal, there is no evidence that they crossed the Atlantic or that they entered the Atlantic through the Panama Canal. Besides, it is very unlikely that the tropical lionfish could survive a journey across the cold water between the two oceans.

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