Compatibility index
Which aquarium treatments are safe for marine invertebrates?
Corals, anemones, starfish and marine crustaceans. Every treatment in the database, grouped by what its manufacturer actually states — not by what the ingredient list implies.
5 of 24 formulations are stated compatible with marine invertebrates 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 (5)
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 draws a clean line between saltwater and freshwater invertebrates: saltwater inverts and coral are explicitly safe, while the removal instruction applies specifically to freshwater invertebrates. The two statements read as a contradiction only if the words "freshwater" and "saltwater" are dropped.
Seachem StressGuard
Slime coat protectant and stress reducer
Reef aquaria are named explicitly in the safety statement.
Fritz Aquatics Maracyn
Bacterial infection treatment
Fritz marks both saltwater fish and coral compatible in the same table.
API PIMAFIX
Antifungal remedy
API names reef aquariums, live corals and anemones directly in its safety claim.
Fritz Aquatics Maracyn Two
Bacterial infection treatment
Coral and saltwater fish are both marked compatible in the same table.
Permitted, with conditions (3)
Not a refusal and not a clearance — a reduced dose, a species carve-out, or a manufacturer declining to certify.
Fritz Aquatics Expel-P
Internal nematode treatment
Cleared broadly, but Fritz notes tube worms and feather dusters may be negatively affected — worth knowing before dosing a reef system.
Fritz Aquatics Maracyn Oxy
Non-antibiotic oxidising treatment
Coral is cleared, but Fritz singles out starfish and related species as not recommended. A blanket reading of the coral row would miss that carve-out entirely.
Fritz Aquatics Expel-F
Antifungal / nuisance algae treatment
Broadly compatible, with a specific reef caveat: Fritz warns it affects desirable macroalgae and can make some corals retract temporarily. That is a tolerable side effect in a fish-only system and a real consideration in a display reef.
No statement found (10)
We looked and the manufacturer does not address this group. Silence is not a clearance — treat these as unconfirmed.
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 about marine invertebrates was found for this formulation.
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 NeoPlex
Bacterial 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.
API MELAFIX
Antibacterial remedy
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 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 (6)
Named in a warning. Move the livestock or choose another treatment.
Seachem ParaGuard
External parasite and fungal treatment
Seachem states plainly that ParaGuard is not recommended for reef aquaria, alongside the Directions instruction to remove all invertebrates.
Fritz Aquatics Mardel Coppersafe
External parasite treatment (chelated copper)
Corals and jellyfish are named explicitly alongside crustaceans and molluscs.
Seachem Cupramine
External parasite treatment (copper-amine)
Covered by the same blanket instruction to remove all invertebrates.
API Liquid Super Ick Cure
Ich treatment
The same instruction covers saltwater aquariums containing invertebrates.
Seachem KanaPlex
Bacterial and fungal infection treatment
Covered by the same blanket instruction to remove all invertebrates.
Fritz Aquatics FixIck
External parasite treatment
Coral is marked not recommended alongside invertebrates generally.
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.