Wolf eels are more closely related to blennies than true eels. There used to be an outfit in Oregon that sold coldwater fish but I don't think they are still around. I don't know if you understand the term "cold", by coldwater it means you have to have a tank in the 50's, I don't believe there are any aquarium chillers that will chill a tank to those low temperatures. They are found along the coast in Northern California up to Alaska and a small one is over a foot. While they look like they will kill anything in the tank, they usually don't bother smaller fish but feed on shrimps, crabs, clams and other hard shelled inverts, although in fish tanks fish do things they don't normally do in the wild so be careful about tank mates.
There used to be a pair in the touch pool at Steinhardt Aquarium in SF, they are very shy and were very rarely even seen but there were no concerns that anyone with their hands in the pool would be bitten. I am not sure how many of you have been there and seen them but the touch pool I'm talking about was under the round-a-bout for those of you old timers who have been going to the aquarium for as long as I have.