There's an update on the Snakehead saga, which I blogged last week (1,2). ABCNews.com is reporting that the fish were intentionally released into the pond in Maryland in which they were discovered. The report doesn't say whether the culprit came forward or was found out (he/she won't be facing criminal charges, as the statute of limitations has run out). The release of pet fish that outgrow their aquariums or are no longer wanted is fairly common, and is the reason why the ownership of predatory fish like snakeheads and piranha is now outlawed in many states.
ABCNews.com also has a link to this more general story about fish introductions. What was surprising to me was the news that the Lionfish (Pterois spp.), a poisonous fish popular in marine aquariums, has been caught off the Atlantic coast of the U.S., far from its native habitat (the Indian and Pacific Oceans). Though Lionfish tend to be pretty hardy, it is hard to imagine any fish from a salt-water aquarium surviving a dump into the Atlantic.