It's going to happen sooner or later... You treat with Prazipro (or General Cure), wait 5-7 days, do your 25% water change and dose again. And yet flukes remain on the fish. 
One important step you should take when determining when is the best time to administer the second dose is use this treatment calendar: http://www.marineparasites.com/paratreatmentcal.html
It takes water temperature & salinity into consideration, and provides a more accurate dosing schedule than the generic "5-7 days."
But what if you still have flukes despite following the treatment calendar? Well, if you used API General Cure give Prazipro a try next before moving on to other options. The reason is because General Cure only contains a praziquantel concentration of 2.0 mg/L vs. Prazipro's 2.5 mg/L. To be clear, 2.0 mg/L prazi is considered therapeutic; however Prazipro's "overdosed" 2.5 mg/L concentration is obviously going to be more effective. (If you keep having problems with flukes getting through General Cure, I recommend shaking or rolling the canister to be sure the prazi/metro powder ratio is more evenly distributed.)
What if even Prazipro doesn't get the job done?? Below is a list of alternative treatments for flukes, in order of preference:
One important step you should take when determining when is the best time to administer the second dose is use this treatment calendar: http://www.marineparasites.com/paratreatmentcal.html
It takes water temperature & salinity into consideration, and provides a more accurate dosing schedule than the generic "5-7 days."
But what if you still have flukes despite following the treatment calendar? Well, if you used API General Cure give Prazipro a try next before moving on to other options. The reason is because General Cure only contains a praziquantel concentration of 2.0 mg/L vs. Prazipro's 2.5 mg/L. To be clear, 2.0 mg/L prazi is considered therapeutic; however Prazipro's "overdosed" 2.5 mg/L concentration is obviously going to be more effective. (If you keep having problems with flukes getting through General Cure, I recommend shaking or rolling the canister to be sure the prazi/metro powder ratio is more evenly distributed.)
What if even Prazipro doesn't get the job done?? Below is a list of alternative treatments for flukes, in order of preference:
- Fenbendazole: 12 hour bath treatment at 25 mg/L (95 mg/gallon). It would be advisable to transfer the fish into a sterile QT following the bath treatment (to prevent reinfection), and to perform a second bath + transfer 1 week later to eliminate any hatchlings.
- Hyposalinity for 1 week eliminates both juvenile & adult flukes, and prevents egg hatching.
- Formalin: 45 minute bath treatment at 0.6 ml per gallon, or 12 drops per gallon. It would be advisable to transfer the fish into a sterile QT following the bath treatment (to prevent reinfection), and to perform a second bath + transfer 1 week later to eliminate any hatchlings.
- Hydrogen Peroxide (still experimental): 75ppm H2O2 for 30 minutes. To achieve this concentration, dose 0.625 ml of 3% H2O2 per 1 cup of saltwater OR 2.5 ml of 3% H2O2 per 1 liter of saltwater. It would be advisable to transfer the fish into a sterile QT following the bath treatment (to prevent reinfection), and to perform a second bath + transfer 1 week later to eliminate any hatchlings.