It's more than likely the salt residue. My friend was helping me with my tank, and she had red spots on her hands after she had her hands in the tank. Nothing to worry about.
Anyways the lionfish venom has to be triggered from the spine to the gland for it to invenomate you.
- 2 Percula Clowns
2 Emerald Mithrax Crab, 5 Nassarius Snails, 3 Astrea Snails, 1 mexican turbo snails, 1 Chocolate Chip Star, 1 Peppermint Shrimp, and 27lbs of LR
2lbs tonga branch and 25lbs fiji rock
Maiden's Hair, Calerpa, and Red Kelp macro algae.