Fish & shrimp health guide
Ich (White Spot)
Also called white spot, ick, Ichthyophthirius
Grains of white salt scattered over the fins and body, and fish flicking against surfaces.
TL;DR, Ich (White Spot)
Ich is the one nearly everyone meets. It looks like grains of salt stuck to the fins and body, and it usually starts after a chill or a stressed new arrival. The parasite only takes medication during its free-swimming stage, so treatment runs over days, not hours. Raising the temperature speeds its life cycle so the treatment can reach it. The catch in a planted tank is that shrimp and snails hate the usual copper and malachite-green medications, so pick an invert-safe route or move the fish to quarantine.
What you see
White spots the size of salt grains on the fins first, then the body. Fish flick and scratch against hardscape and substrate, clamp their fins, and breathe fast if the gills are hit. Left alone it spreads across the whole fish and through the tank.
What causes it
- A temperature drop or swing that stresses the fish
- A new fish added without quarantine bringing the parasite in
- Chronic stress from poor water or bullying lowering resistance
How to treat it
- Raise the temperature slowly to around 28°C to speed the parasite's cycle, if all your fish tolerate it.
- Treat with an invert-safe white spot medication, or use the heat-and-salt method in a fish-only tank.
- Keep treating for the full course, several days past the last visible spot, since medication only kills the free-swimming stage.
- Increase aeration, because warmer water holds less oxygen.
- Do the recommended water changes between doses to clear dead parasites.
Treatment safety in a planted tank
Copper and malachite-green medications kill shrimp and snails and harm scaleless fish like loaches and corydoras. In a stocked planted tank use an invert-safe formula at the stated dose, or move affected fish to a bare quarantine tank for stronger treatment.
Prevent it
Quarantine new fish for two weeks, avoid temperature swings, and keep the tank stable. A calm, well-fed fish shrugs off the odd parasite that a stressed one cannot.
Easy to confuse with
Velvet looks like a finer gold or rust dust rather than distinct salt grains. Breeding tubercles on male fish and the white spots of columnaris are also mistaken for ich, but neither spreads as scattered grains.
Species most at risk
Species that catch this most often, or that need a gentler treatment:
- Kuhli Loach — Scaleless, so it reacts badly to copper and malachite green, use invert-safe or quarantine treatment.
- Otocinclus (Common) — Delicate and med-sensitive, treat gently and keep oxygen high.
- Pygmy Corydoras — A small scaleless catfish that needs the gentler treatment route.
- Neon Tetra — A classic early victim, especially just after a temperature drop.
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
Is ich contagious to my whole tank?
Yes. Once the parasite drops off and reproduces, it targets every fish. Treat the whole tank, not just the spotted fish.
Can I just raise the temperature to cure it?
Heat speeds the cycle so treatment reaches the parasite faster, but on its own it is unreliable. Pair it with an invert-safe medication or salt in a fish-only tank.
Will ich medication kill my shrimp?
The common copper and malachite-green ones will. Use a formula labelled shrimp and snail safe, or treat the fish in a separate tank.