Jos: When you get your larger tank, you might want to look into cycling it. :) Here's a good link if you wanna glance over it. http://www.fishlore.com/NitrogenCycle.htm
Also, for feeding him, be sure to fast Zombie an entire day once a week to clear out his digestive system. Because he's eating a good bit, but doesn't have enough room to burn off the engery by swimming alot. If you want him to exercise and give him something to do, and if you have a small hand held mirror or something reflective, you can hold it up for Zombie to see so he will flare at it. One to two minutes of flaring will burn a lot of energy on his part. If you do this though, don't do it for too long, otherwise he will get stressed.