Is your eel in with all your fish? Just so you know I have seen a snowflake take out some pretty big fish including a fairly large lion.
Regarding triggers, I used to have a niger in my reef several years ago and loved it however when I upgraded my tank and moved it to the back tank it actually ate my bicolor angel on day.
Fish are always hit & miss but if you get a bad one look out! Also they can change behavior even after being in a tank for several years.
One of the interesting aspects of this hobby is we put fish together in our tanks from all over the world and many that often don't live together in the wild and they can teach each other new tricks - some of which are not good.
