Ingredient risk record
Metronidazole
Also appears as: metro
An antiprotozoal and antibacterial used against internal parasites, most often paired with praziquantel. It is one of the clearest demonstrations that formulation matters more than chemistry: Fritz ParaCleanse and API General Cure both use it, but only Fritz states the product is invertebrate safe. API simply does not address shrimp or snails at all.
Source-linked caution for
The evidence is formulation associated. It raises a warning on a product containing this ingredient but never decides the verdict.
“Safe for plants and invertebrates.”
manufacturer page · fritzaquatics.com · checked August 16, 2026
The inference only runs one way
A product containing metronidazole gets a warning. But a product without it gets nothing — no clearance, no green tick. Fritz Algae Clean Out contains no copper and is still explicitly unsafe for shrimp and snails, which is why FishyMag will not certify a product as compatible unless the manufacturer says so directly.
Treatments containing metronidazole
Next steps
FishyMag reports what manufacturers say, quoted and linked. It does not diagnose illness or recommend a treatment, and it never infers that a product is safe from the absence of a warning — where no statement exists, it says so.
Formulations change. Always read the label on the bottle in your hand, and contact the manufacturer if your tank contains anything valuable or unusual.