I had one for about 7yrs. I got from liveaquaria at around 18" and it grew over 36" in that time. It was a big powerful eel, over 2.5" thick. I would suggest at least 120-125g tank with heavy filtration. They can be pretty active/destructive when hungry. At times he did knock over pieces of the rock work. I used pvc pipe under the liverock to create tunnels for eel, this gave it a dark place to feel comfortable. I think started with 1.5" pvc and ended up using 3" before I get rid of him because I had to take down the tank. Like all eels they have poor eye sight and rely on smell when feeding. He was a great tank mate and didn't bother any other fish, but did get excited around feeding time and did kill one fish that swam in front of its mouth at the exact moment he was about to clamp down on a piece of shrimp. I fed it raw shrimp, smelt, squid, mussels, and other seafood you can buy at the grocery store. I soaked all the food in Selcon to add whatever the food maybe lacking. I used a long pair of aquarium tweezers to target feed the eel. Be careful when choosing tank mates. Because zebra eels and eels in general are pretty sedintary some fish might pick at it, like angles, triggers, and even tangs. That being said I did keep mine with a yellow and blue hippo tang and a sargassum trigger without issues. One last note like all eels if there is a way escape they will find it eventually. So make sure the top of tank is closed off tightly.
Overall a great fish. I'm actually setting the tank back up and plan on buying one again.