Although I have not tried Praziquantel on gill fluke infestation (Gyrodactylus), Prazi product worked well on certain internal worm infestations including both internal trematodes/cestodes.
The fluke mentioned in above link is about internal trematode (sometimes referred to as fluke) infestation but not Gyrodactylus, an external paraiste..
If gill flukes on Steph's fish are Gyrodactylus (livebearing fluke), I would prefer Formalin based med over Prazi as specified by parasitology books and meds I tried.
Well, provided that this is gyrodactylus to begin with as they are at or smaller than 1 mm long which may not be correctly id by naked eyes.
By all means, I am not discrediting others experiences, just pointing out the simple facts.
Unless confirmed this is Gyrodactylus infestations, I really dont know which med to use. If one feels this is definitely Gyrodactylus, more than one fish may be infested.
Perhaps divide them into two different groups in separate q/t (but same water condition) and try diffferent meds and record the results.
Can someone provide ingredients on life-bearer? I am thinking it is based on Formaldehyde as well.
Good Luck!