Underwater World - Menacing

Digital Photo taken in Queensland, Australia at Underwater World. Shot through rather thick perspex or glass.

No cropping, but slight contrast and brightness adjustments made.

I'm not entirely sure what this creature is called, other than knowing that it's a very dangerous critter. I know it was in the same tank as a few Stonefish (which themselves are rather toxic creatures) but didn't seem troubled by them.

Although rather colourful, I'm not sure I'd stick around if I happened across this critter. Something about it just screams "beware!" don't you think?

Thanks to a very helpful commenter, this has been identified as a Lionfish. From Wikipedia [link] :
The NOAA encourages everyone (divers and fishers) to be extremely cautious and avoid contact with the venomous spikes of the lionfish. Usually, lionfish are not aggressive toward humans and will almost always keep their distance when given the opportunity, so they pose a relatively low risk. In addition, their stings are not deadly, but they are very painful.

The lionfish is one of the most venomous fish on the ocean floor. Lionfish have venomous dorsal spines that are used purely for defense. When threatened, the fish often faces its attacker in an upside down posture which brings its spines to bear. However, a lionfish's sting is usually not fatal to humans. If a human is envenomed, that person will experience extreme pain, and possibly headaches, vomiting, and breathing difficulties. A common treatment is soaking the afflicted area in hot water, as very few hospitals carry specific treatments. However, immediate emergency medical treatment is still advised, as some people are more susceptible to the venom than others.