Fully quarantined Clown recently has white stringy poop?

[lagatbezan]

Within the last few weeks I have noticed that my female clown fish occasionally has white stringy poop hanging from it. And tonight I saw the male one with the same. They have been in my tank for more than 4 years and everything that goes in the tank goes through a full 30 days qt with tt and 2-3 rounds of prazipro. Also nothing new has been added to the tank for about a year. They are still eating fine. They used to lay eggs every few weeks but for whatever reason that stopped about 6 months ago. Their main diet is NLS pellets, flakes, whatever seaweed floats their way and occasionally some frozen. I know white stringy poop could be signs of internal parasites, but can it be now after so long?
Should I treat? If so with what? I have almost any med on hand (benefits of doing qt).
Any advice would be appreciated.

 

[Newsmyrna80]

My clown had that off and on for over 10 years and it didn't slow her down.

 

[lagatbezan]

thanks Newsmyrna80. I was thinking of medicating the food, but I decided not to since its on/off.
any ideas on why they stopped spawning?