internal parasite?

[trouthead]

I have noticed a danio with a long pale faecal trail. I know that this is an indication of an internal parasite. I don't however know whether to treat the tank now, or wait for further symptoms (or fish with similar symptoms). i.e. how strong is this diagnosis on a single sighting?

 

[Avalon]

Hmmm...this may not yet indicate an internal parasite. If the feces was in a spiral shape, it could very well be an internal parasite. Feed well. Give it a couple of days and see if this persists. If it does, there's no reason that you cannot medicate. A good med is Seachem's Metrozindazole. It is very safe to all fish, and is very effective at curing IP's. If one of your fish has it, you should consider that all of your fish might have it, even if there are no symptoms. Better to be safe than sorry.