Just keep an eye on them. Although like most fish they will keep an eye on you too and usually stay away. Dont Hand feed or they will think its feeding time all the time. Hope this helps.
I got stung by Lion once. it hurts like hell.... Like a bee sting.
Normally, they would respect your job (cleaning) unless you want to know what it likes to be stung
i second the magnetic scraper... i try not to feed my lion fish by hand but... ever time you even look at the tank he is there.. he likes the attention i guess..
sticking your hand in my aggressive tank is not advisable..
Used to have a fu-man-chu lion while I was in college that would flip over and stick his belly out of the tank and wait to get scratched. Cutest damn fish in the world, very friendly and outgoing for a lion. Sucks because I lost him when my yellow box kicked off for no apparent reason and toxified the tank (it was my first marine tank ever).
I Kept a lion fish for a year until I killed him by overfeeding. That is easy to do. They act so happy when they get fed.
He stung me once, totally my fault. It really helps to turn off all circulation if you are going to be moving things around in the tank as you can get a really distorted view from above with the water rippling. That is what happened to me. It looked to me from above like I was about 6" away, but my wife yelled just about the same time I got stung because she saw from the front how close I was. Hurt for about three days, of course I have a slight allergy to bees also.
My lion has bit my hand about 3 different times, mostly because I was trying to get him to do it. When I clean the tank he runs like a little girl. Just scare them away with your algae brush.
Don't let them get too chummy I have a venomous fang blenny who is fairly aggressive and also a coral catfish who have a nasty venom. Just be aware of where they are and a good investment might be some of those aquagloves to prevent actually getting stuck.
When I put my hands in my tank, the wrasses and trigger like to nibble on my wedding band 8O. No fear of my hands at all. I could probably tickle them if I wanted. No scorpion for me.
make sure you know just how dangerous your livestock is before you buy. lionfish are like a bee apparently, while marine catfish (plotosidae lineatus) are quite close to deadly, apparently. my new 150 gal will contain a trio of p. lineatus, and i will be writing down the scientific name and a what-to-do-if for my family in case i ever get envenomized. as far as i know, the best thing you can do for a sting from any livestock is soak it under as hot of water as you can handle, and certainly call the hospital or poison control centre.