fish parasites

Question
My damsel had bite on it's upper side. Also a white string hung under the fish. After it died I bagged it and squeezed it and a small white (parasite?) came out of it and swam in the plastic bag. Do I need to treat the tank and what do I use that won't kill my salt water hermit crab?

Answer
Kent Marine RxPTM will treat a number of parasites without harming most other things in your tank, works better than copper, yet leaves no residual toxic metals after treatment.

Do not use with lionfish, stonefish, scorpion fish, starfish, sea urchins, medusa worms, sea apples, sea cucumbers or nudibranchs.

it sounds to me like it was some kind of internal roundworm though, Hikari makes a product called Prazi-Pro in which the active ingredient is Praziquantel, also, Gel-Tek makes a product called  Ultra Cure PX, which contains  metronidazole, flubenol and praziquantel, all of which are de-wormers.

if you have no other fish showing signs of bloated bellies and stringy appearing excrement then i wouldn't bother dosing with anything. if you notice the above symptoms on any other fish then i would treat them in a small quarantine tank.