I would assume poor water conditions and diet
Without a lot of details I’ve got no real advice besides several large water changes and improved diet.
I like algae based pellets in an autofeeder and frozen mysis as a foundation of a decent diet
Why not run the cord up and use the cable ties like you’re supposed to?
I dont know if I made this up, but I seem to remember you’re supposed to run them with the cord up for some (mechanical?) reason besides holding the in place.