I'll throw in my 2 cents: Before i bought my first SFE, i did a ton of reading on them and new they were jumpers, so before i got him and set up his new tank in my system, i sealed off all the holes, put screen in my HOB filter intake and outputs, and ductaped the glass top down every were but one spot that would serve as my access point, with a weight on top. Confident that i had the tank secure, i had it ready to go inline with my other tanks, and everything was good so i brought him home. After a week or normal life, he ate on the first day i got him, and did so like a little pig, i woke up for a 8am class and found him dried up on my entry way tile. i was baffled as how i could have been so stupid, and i had to figure out how he got out. turns out there was a small gap, around a eighth of an inch under the U tube connect to the intake where the filter didnt make a perfect seal with the edge of the tank. Needless to say that hole was patched and after the addition of the next eel, that i still have to this day, i woke up every few hours the week after i got him out of total paranoia. They really are the Houdini's of the saltwater tank.