Formulation evidence record
Seachem ParaGuard
External parasite and fungal treatment · US formulation
Shrimp
Amano, cherry, crystal and other freshwater shrimp.
Snails
Nerite, mystery, ramshorn and other aquarium snails.
Live plants
Rooted and floating live aquarium plants.
Scaleless fish
Loaches, corydoras, plecos, eels and other scaleless species.
Marine invertebrates
Corals, anemones, starfish and marine crustaceans.
Not addressed by the manufacturer for: biological filter. No statement was found, so no verdict is given — that is not a clearance.
Why FishyMag says this
The manufacturer's own wording, quoted rather than paraphrased, so you can judge it yourself.
Shrimp
Manufacturer advises againstSeachem's Directions open by instructing keepers to remove all invertebrates before dosing. Their FAQ is softer — they decline to certify the product as invert safe rather than forbidding it — but an instruction in the Directions outranks a hedge in the FAQ, so this is recorded as advise-against.
Contains aldehydes, with a source-linked caution associated with this group. This raises a flag—it is not the basis of the verdict above.
“Remove all invertebrates from the tank as well as any chemical filtration”
manufacturer page · seachem.com · checked August 16, 2026
“We do not sell or market ParaGuard™ as invert safe because it would be impossible to test it with every available invert under every potential water parameter.”
manufacturer faq · seachem.com · checked August 16, 2026
Snails
Manufacturer advises againstSnails are invertebrates and fall under the same opening instruction in the Directions to remove all invertebrates before dosing.
Contains aldehydes, with a source-linked caution associated with this group. This raises a flag—it is not the basis of the verdict above.
“Remove all invertebrates from the tank as well as any chemical filtration”
manufacturer page · seachem.com · checked August 16, 2026
“We do not sell or market ParaGuard™ as invert safe because it would be impossible to test it with every available invert under every potential water parameter.”
manufacturer faq · seachem.com · checked August 16, 2026
Live plants
CautionSeachem describes it as generally safe in planted aquaria, but frames this as their experience rather than a tested guarantee. That is weaker than a label claim, so it is recorded as caution rather than compatible.
“generally safe to use in planted aquaria”
manufacturer faq · seachem.com · checked August 16, 2026
Scaleless fish
CautionPermitted, with an explicit instruction to start low. Seachem says scaleless species can be more sensitive and recommends beginning at a quarter to half dose before building up.
Contains malachite green, with a source-linked caution associated with this group. This raises a flag—it is not the basis of the verdict above.
“You can use any of our medications with scaleless fish, but as they can be more sensitive, we would recommend that you begin with a 1/4 to 1/2 dose first and slowly build to the recommended dosage.”
manufacturer faq · seachem.com · checked August 16, 2026
Marine invertebrates
Manufacturer advises againstSeachem states plainly that ParaGuard is not recommended for reef aquaria, alongside the Directions instruction to remove all invertebrates.
Contains aldehydes, with a source-linked caution associated with this group. This raises a flag—it is not the basis of the verdict above.
“Remove all invertebrates from the tank as well as any chemical filtration”
manufacturer page · seachem.com · checked August 16, 2026
“We do not sell or market ParaGuard™ as invert safe because it would be impossible to test it with every available invert under every potential water parameter.”
manufacturer faq · seachem.com · checked August 16, 2026
Product details
- Manufacturer states it treats
- External parasites, Fungal infections, Bacterial and viral lesions
- Chemical filtration
- Remove chemical filtration during treatment
- Ingredients as stated
- A proprietary, synergistic blend of aldehydes, malachite green and fish protective polymers (10% aldehydes by weight).
- Active ingredients
- AldehydesMalachite green
manufacturer page · seachem.com · checked August 16, 2026
Record last checked August 16, 2026 · confidence high
Check against your tank
Change what is in your tank to see how the answer moves.
External parasite and fungal treatment · US formulation
The manufacturer advises against using this with your tank.
At least one thing you listed is named in a warning. Move that livestock to another tank, or choose a different treatment.
This answers for the assumed selection above, not a tank you have described. Adjust it if it is not yours.
- ShrimpManufacturer advises against
Seachem's Directions open by instructing keepers to remove all invertebrates before dosing. Their FAQ is softer — they decline to certify the product as invert safe rather than forbidding it — but an instruction in the Directions outranks a hedge in the FAQ, so this is recorded as advise-against.
- SnailsManufacturer advises against
Snails are invertebrates and fall under the same opening instruction in the Directions to remove all invertebrates before dosing.
- Live plantsCaution
Seachem describes it as generally safe in planted aquaria, but frames this as their experience rather than a tested guarantee. That is weaker than a label claim, so it is recorded as caution rather than compatible.
See the manufacturer’s exact wording and sources for Seachem ParaGuard →
No evidence found means no manufacturer statement was found — not that the product is safe. FishyMag does not diagnose disease or recommend treatments.
Other treatments
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.