On the feeding front variety is always good as long as you know they come from a none contaminated source I would say yes.
One thing I have seen and would like to try would be a group of very small fish, tetras etc but the wolf needs to be large for this to work. My small one which is now about 17" is still to small and would eat them up. The second about 20+" haven't measured him for ages is with some brycon and a large ATF, they would definatly eat them.
You have motivated me to sort my gravel out now.