The medication began as precaution during quarantine. I noticed the batfish had stringy white poop and initially thought the Prazipro would work. I ordered Seachem because the batfish still has an appetite but is losing color. The 2 weeks of treatment just finished, so I put charcoal in today. I will get the Seachem tomorrow.
It's best not to use any meds unless a fish is sick and you can identify the illness. It does no good to medicate a fish if there is no disease present; nor medicate randomly when you don't know what you are treating. If medications are used excessively, then resistances to that med will develop and it won't be useful when you actually do need it.
It is not a bad idea, however, to use hyposalinity in bony fish in quarantine. Observation of fish health is your first line of defense during the quarantine process.
Stringy poop in and of itself doesn't necessarily have significance.