Active ingredient: FritzZyme 7: Live freshwater nitrifying bacteria. Fritz Complete: Sodium formaldehyde sulfoxylate
How to use (from the label): New system: 4 oz (119 mL) per 10 US gal (38 L); no repeat needed (can be raised up to 10x for heavy stocking). Maintenance: 1 oz (30 mL) per 10 US gal (38 L) when adding livestock, replacing filter media or after medication. Prep: remove chlorine/chloramine first; UV off before and for 4 days after; shake; add livestock within 24 h; test ammonia/nitrite daily. Fritz Complete: 5 mL per 50 US gal (189 L); up to 5x within 24 h for very high ammonia
Careful: FritzZyme 7: Compatible with all freshwater species incl. snails/invertebrates, plants, amphibians; non-toxic even if no longer viable; medications may kill the bacteria (re-dose after treatment). Fritz Complete: Above 30 °C, repeated doses can quickly lower dissolved oxygen, so aerate well; Nessler ammonia tests read wrong; can interfere with some ich treatments (e.g. Ich-X)
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: FritzZyme 7 (freshwater), Fritz Complete. Not endorsements. Always follow the label.
5 facts checked with sources