"My fish has ich" is one of the most common things we hear, but saltwater ich and freshwater ich are actually caused by different parasites entirely — and treating one like the other won't work.

The Short Answer

Both show up as small white spots on the skin, fins, and gills, and both are usually triggered by stress. But the parasite, and the safe treatment, differs by tank type.

Saltwater (Marine) Ich

Caused by a marine-specific parasite that attaches to fish. Typically treated in a dedicated hospital/quarantine tank using medication or a hyposalinity protocol — most ich treatments aren't safe to use in a display tank with coral or invertebrates.

Freshwater Ich

A different parasite, though the visible symptoms look similar. Usually treated with a combination of raised temperature, medication, and improved water quality, typically in a separate quarantine tank.

What They Have in Common

• Both are often triggered or worsened by stress — a recent move, a temperature swing, or poor water quality.
• Both are best treated away from your main display, not in it.
• Both are far easier to prevent than treat — a proper quarantine period for new arrivals is the single best defense.

Not sure which one you're looking at, or how to proceed? Give us a call — we're happy to help you figure out the right approach before you medicate the wrong tank.

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