Do you feed bloodworms.
White stringy poo can mean bacterial infection, constipation, internal parasites.
Signs of internal parasites are
Long stringy white poo, clear mucas poo, red poo.
Worms sticking out of the anus.
Enlarged anus.
Red inflamed anus.
Fish will look skinny or bloated.
Sunken in belly.
Bent spine sometimes.
Sometimes fish will swim on it's side.
Flicking and rubbing.
Not eating.