Compatibility index
Which aquarium treatments are safe for the biological filter?
The nitrifying bacteria in your filter media. Every treatment in the database, grouped by what its manufacturer actually states — not by what the ingredient list implies.
4 of 24 formulations are stated compatible with biological filter by the manufacturer.
The rest are qualified, contradicted, or simply never addressed — which is why counting green ticks is the wrong way to read this page.
The manufacturer states it is compatible (4)
A positive claim from the people who make the product. This is the only group where a manufacturer has actually said yes.
Fritz Aquatics Algae Clean Out
Algae treatment
Fritz states the product does not affect biological filtration, so your cycle should not crash during treatment.
Seachem NeoPlex
Bacterial infection treatment
Seachem lists NeoPlex as having minimal impact on the biological filter.
API MELAFIX
Antibacterial remedy
API states MELAFIX will not adversely affect the biological filter, alter pH or discolour the water.
API PIMAFIX
Antifungal remedy
API states PIMAFIX will not harm the biological filter.
Permitted, with conditions (1)
Not a refusal and not a clearance — a reduced dose, a species carve-out, or a manufacturer declining to certify.
Sources disagree (1)
Credible sources contradict each other, sometimes on the same page. Both are shown on the record so you can judge.
No statement found (17)
We looked and the manufacturer does not address this group. Silence is not a clearance — treat these as unconfirmed.
Seachem ParaGuard
External parasite and fungal treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Fritz Aquatics Mardel Coppersafe
External parasite treatment (chelated copper)
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Seachem Cupramine
External parasite treatment (copper-amine)
Seachem does not address effects on biological filtration in its Cupramine documentation.
API Liquid Super Ick Cure
Ich treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Seachem MetroPlex
Protozoan parasite and anaerobic bacterial treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check before dosing.
Seachem PolyGuard
Broad-spectrum bacterial, fungal and parasitic treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check before dosing.
Fritz Aquatics PraziCleanse
Anthelmintic (deworming) treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check before dosing.
API General Cure
Internal and external parasite treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Fritz Aquatics ParaCleanse
Internal parasite treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Seachem KanaPlex
Bacterial and fungal infection treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Seachem Focus
Medication binder for medicated food
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Seachem StressGuard
Slime coat protectant and stress reducer
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Seachem SulfaPlex
Bacterial and fungal infection treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Fritz Aquatics Maracyn Oxy
Non-antibiotic oxidising treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Fritz Aquatics FixIck
External parasite treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Fritz Aquatics Expel-F
Antifungal / nuisance algae treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
Fritz Aquatics MetroCleanse
Internal parasite treatment
No statement from the manufacturer was found for this group. Treat it as unconfirmed and check with the manufacturer before dosing.
The manufacturer advises against it (1)
Named in a warning. Move the livestock or choose another treatment.
Other livestock
No evidence found means no manufacturer statement was found, not that a product is safe. Dataset last checked August 16, 2026.
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.