It's brown at the end of a thin white or clear threadI cant tell too well from the pics but is it white or clear? I see some brown bits, I think.
Generally white + stringy is going to indicate intestinal flagellates or worms. Course of action there is 1 tblsp of food + 1 scoop of focus + 1 scoop general cure (focus should make it reef safe)
Fathead/Sunburst anthias are generally less active than most, so they don't eat quite as much. This one definitely went a couple days not eating much, if anything, so it's possible it's the same as what you saw with your clownfish.I know less than anyone about fish parasites
I have moved a clown fish a few times when changing homes. After the move, the clown would sometimes go a day or two or three (always scary) before eating what I feed. I would sometimes see similar poop, that your pic shows, shortly after he began eating again. It always catches my eye because over so many years i had rarely ever seen him poop. I figured, in my clowns case, it might be because of the days of not eating, then booting back up.
I know anthias eat a ton and not sure if this could even be food related. Not sure if an anthia could go a couple few days without eating and survive like a clown could.
Thanks, this seems like the issue, especially because there was some brown in it..White Stringy Poop in Fish - Aquatic Veterinary Services
Alright, we’ve cleared up the internet’s favorite fish diagnoses: swim bladder, dropsy, constipation and mystical green peas, but what about that “white stringy poop?” Somehow, many internet diagnoses involve this mysterious phenomenon in fish and have linked it to internal parasites. Well, let...cafishvet.com
Here is an article I referenced for a similar question I had, it seems that when they haven't eaten they can just have white poop from time to time without it being a sign of disease, I noticed it on a kole tang once right after I bought it before it had eaten much. Went away really fast after I fed often