Ingredient risk record
Gentian violet
Also appears as: crystal violet, methylrosanilinium chloride
A dye used against external parasites and fungal infection. Fritz marks it not recommended for snails and other invertebrates, coral and amphibians, and describes plant tolerance as depending on species rather than clearing plants outright.
Source-linked caution for
The evidence is formulation associated. It raises a warning on a product containing this ingredient but never decides the verdict.
“Snails and other invertebrates Not recommended”
manufacturer page · fritzaquatics.com · checked August 16, 2026
The inference only runs one way
A product containing gentian violet 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 gentian violet
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.