Experiments show Lionfish are a danger in the Bahamas

"PhD student Mark Albins of Hixon’s team devised a controlled experiment testing the effects of lionfish on native fish communities by documenting the recruitment of newly settled reef fishes on 20 patch reefs near LSI: 10 reefs with a lionfish and 10 reefs without. Fish censuses were conducted at one week intervals for five weeks. Recruitment was significantly lower on lionfish reefs than on control reefs at the end of the experiment. On one occasion, a lionfish was observed consuming 20 small wrasses during a 30 minute period.

It was not unusual to observe lionfish consuming prey up to 2/3 of its own length. Results of the experiment show that lionfish significantly reduce the net recruitment of coral reef fishes by an estimated 80%. The huge reduction in recruitment is due to predation and may eventually result in substantial, negative ecosystem-wide consequences. It is also important to note that lionfish have the potential to act synergistically with other existing stressors, such as climate change, overfishing, and pollution, making this invasion of particular concern for the future of Atlantic coral reefs."

I've seen them with my own eyes, although very beautiful, I have come to know that they are dangerous.  Based on the above, the whole article can be seen here  Spearing them is easy, and Stuart Cove's has some very good instructors & masters who are very proficient with these weapons and can teach you very easily.  I would recommend a great weekend of sunning & diving in the Bahamas, and doing something for the environment by getting rid of these fish.