Anybody that kept a moray in a topless tank for any length of time should play the lottery. They will find the smallest of gaps and end up on your floor. I have had it happen multiple times (with large tanks, full of rock). They ALWAYS find a way out lol...it is only a matter of time. Your odds are better if you make it past the first couple of weeks though. To answer the original question though, I have kept them successfully with screen tops, although if the moray was big enough and determined, it could probably push the top up.
Lol, the lottery part isn't working yet.
And yes, that is what I read everywhere. That they would climb out faster than an octopus if you gave them even the tiniest option.
Other than the fact that the tank was mostly rockwork with more "hiding space" than open water, I can only attribute it to being one individual eel.
Lol, seriously, the whole tank was a 'fish only' open cube of white rock. Maybe 3" to 4" clear water space above everywhere except for a 6" open feeding area.
Lousy 'fish only' lighting that would barely support caulerpa directly under it. No coralline in the tank. My other build is called Hotel Coralline.
(This may have been a huge factor. They don't like sps lighting, supposedly.)
"snow" was never an escape artist. Not even once. Not even when it went on a 2 month hunger strike and died inside the tank after 6 years.
Seldom even stuck it's head above water even when it was ready to feed. Fed it like a snake.
If it was out and curious for a day it was time to feed.
Once a week, often once every 3 weeks as it got larger.
2 or 3 IQF small thawed silversides.
Then read they were too oily. Bad owner, etc.
Tried transitioning to large krill and shrimp and wasn't having any of it.
Tried going back to silversides and wasn't interested anymore.
First feeding attempt with krill was at the usual 3 week mark. Then another 2 months of not eating before it died.
All still inside the tank with the front lid open.
That's just one person's experience with 1 eel. Everyone else says they will jump out of the tank in a heartbeat.
:-/