OK in all my years of fishkeeping I've never had this happen. Somehow one of my angelfish swallowed a thread that was used to tie plants to driftwood. The string is visibly hanging out of its anus but the fish isn't able to completely pass it. I've tried pulling the thread out but I've tugged pretty hard and it won't budge. I'm afraid it might block it's passage but it's still eating fine and doesn't look bloated. What are people's suggestions on helping this guy out?