Ash, I usually work from outside of the tank, using tongs, a net, or a long siphon hose to avoid putting my fingers at risk. In the event that I do need to actually put my hand in one of the wolf tanks, I make sure that they're very well fed (offer food until they're no longer interested in it) and then move all of the floating cover out of the way with a large net and keep my eyes on them. I always put a fist into the water, never fingers first. I hope that they're less likely to mistake a whole hand coming in at once as a food item as compared to a finger breaking the water surface. Overall, though, I try to avoid putting hands in those tanks whenever possible.
pbecot01, if you know of another free video upload site I'll give it a whirl. Putfile is simply the only one that I've found so far.