I have had problems with the carpet I have too. But I think the fish and critters can escape if it is just a sting. In one case it ate my yellow tang. I had a GFCI trip during the night and the fish were panting when I woke up. The yellow tang (the biggest fish in my tank) was weak and probably got stuck. I saw my flame angel (second biggest) dead in one spot but could not find the yellow anywhere. Later that evening I saw the carpet spill out just the bones of the yellow tang. I fed the thing my dead angel too and it ate it too. They sure can eat. The other victim was a chromis during the tank move. You know the fish all run for safety and my fishes ran toward the only rock I had near the carpet. There was another chromis that was chasing this one so it probably got stuck really bad when running away. I later saw the carpet spill out the half digested chromis when I moved it. Recently I thought the carpet had my skunk cleaner shrimp too since I saw it spit out the whole shell but found out it was only the molt. The shrimps constantly touch the carpet and seems to get stuck but it only had a few legs stuck and can move out. But if a fish chase another one towards the carpet and touches it at full impact, it will get stuck bad and carpet will also know there is some food and close its mouth around it.
The carpet can kill the fish in the long run but if your fish don't fight they might be okay. I think they too understand that there is danger there. It's the new fish that might stumble upon it unknowingly. I will surely keep a moonlight so it's not completely dark at night.
