Active ingredient: Praziquantel powder: praziquantel. API General Cure: metronidazole 500 mg + praziquantel 150 mg per teaspoon
How to use (from the label): Praziquantel immersion: about 2 mg/L for at least 24 h with a repeat 3 weeks later for egg-laying flukes (UK Fluke-Solve), or 2.7 mg/L with a repeat on day 8 (US Prazi-Med); remove carbon/chemical filtration and keep aeration. API General Cure: 1 packet per 10 US gal (38 L), repeat after 48 h, then 25% water change after another 48 h. Follow each product's label.
Careful: Do not use in Callichthyidae (e.g. Corydoras) or Clariidae catfish (Prazi-Med label); use with caution with invertebrates and plants; aerate well; user should wear gloves, eye protection and dust mask with the powder. API General Cure contains metronidazole (California Prop 65 cancer warning).
Rules: US: Prazi-Med is FDA-indexed (MIF 900-054) for ornamental fish only; not for fish used as human food; extra-label use prohibited. API General Cure is unapproved ('not found by FDA to be safe and effective') and not for food fish. Prescription status elsewhere: not confirmed.
Never mix medicines unless the label says it is safe, and remove shrimp and snails unless the label says they are safe.
Examples you may see in shops: Praziquantel powder, API General Cure. Not endorsements. Always follow the label.
5 facts checked with sources