Parasite?

2 weeks ago I got s pair of clowns one med black and one orange (ocelleris).



4 days ago the black one died after a miserable 8 days. I never was able to diagnose him.. Always gasping for air at the top and never ate once.



My other little guy is still alive and has eaten at every feeding. I have never seen him poop until before there was an inch long stringy poop hanging off him for like a minute. It wasn't really white it looked Orange to me.. But maybe that's just my crappy qt lighting... And it was gone after s min, this was 5 min after he ate also.



10 days ago or so I treated the tank w/ prazipro as I thought that might solve the other fishes problem, but it was during the tank transfer process. So the fish only received treatment for 2 days max.



He has been acting normal swimming around , staying in his pvc 90% of the time.



Should I treat with prazipro, or what till I see other signs of a parasite issue?



I was excited and planning on going to get a new clown(black snow ) tomorrow. Do I have to or Should I hold off bc of this poop?