If it is THAT stuck that you might crack the bulkhead of glass, then yes, don't chance it. But the pliers might just give you better grip to get the pvc apart without applying so much force to be dangerous.

Good that you got him out, but wondering if it does it again could you just remove the Durso and let him ride the overflow to the sump?

I suppose that's an option if the piping is large enough and doesn't have too many bends. I'd be afraid of the fish getting stuck somewhere ... what then?

But it's something I'd probably consider if all other options fail.

I tried using a big pair of pliers and couldn't budge it. It must be encrusted with calcium deposits or something. Other than the delinquant fish in the overflow, I have no other reason to remove it. I plan to put some finer mesh on the to to keep fish out in the future. I think this fellow swam in through the eggcrate baffle.

BTW, I'm not worried about the bulkhead cracking, when I had the tank built the guy supplied me with 2" schedule 80 bulkheads. Those things are huge and tough.

I tried that (I kept the net below the water line in the sump), but when the sump was draining, he fought the current like a demon, and wound up behind the bulkhead in the 1" of water remaining. I'm actually glad it worked out like that, since it would have been a stressful waterslide for the poor bugger.

Good luck my six line has lived in my overflow for about a year. Ive tried numerous times to get him out with no luck.