How to Treat Ich (White Spot Disease) in Aquarium Fish

Ich (white spot disease) is one of those problems every fishkeeper meets sooner or later. The good news: it's very treatable if you catch it early and don't panic-bomb the tank with random meds. This is the approach I use-practical, repeatable, and safe for most community setups.

What Ich Actually Is (and why it keeps "coming back")

Ich is caused by a parasite (Ichthyophthirius multifiliis). The annoying part is its life cycle. The white dots you see on the fish are the parasite tucked under the skin/gills-at that stage, meds don't really touch it. Treatment works when the parasite drops off the fish, multiplies in the substrate/decor, and then releases free-swimming "seekers" that go looking for a host. That's the window you're targeting.

How to Spot Ich Early (before it turns into a mess)

Classic ich looks like someone sprinkled salt or sugar on your fish: tiny white grains on fins and body. But I've learned to watch behavior first, because the spots can show up late or be hard to see on light-colored fish.

• Flashing: fish rub/scratch on plants, rocks, heater, glass
• Clamped fins and "I don't feel good" posture
• Hiding more than usual (or hanging in a corner)
• Rapid breathing or hanging near the filter output (gill irritation)
• Reduced appetite (some still eat at first-don't let that fool you)
• White dots that multiply over 24-72 hours

First 30 Minutes: What I Do the Moment I Suspect Ich

Your goal is to reduce stress and get set up for treatment without making the water worse. Most ich outbreaks are helped (or triggered) by stress: temperature swings, ammonia/nitrite, new fish, shipping, bullying, or a tank that's a little overdue for maintenance.

1. Test water (ammonia, nitrite, nitrate). If ammonia/nitrite aren't zero, do a water change right now.
2. Do a 30-50% water change with temp-matched, dechlorinated water. Vacuum the substrate lightly if you can.
3. Turn off UV sterilizer (if you have one) and remove chemical media like activated carbon-carbon will eat many meds.
4. Increase surface agitation (aim filter output up, add an airstone). Treatments and higher temps both lower oxygen.
5. Decide whether you're treating the main tank or a hospital tank (I usually treat the main tank unless I'm dealing with a single new fish in quarantine).

Treatment Options (pick one plan and commit)

There are a few good ways to beat ich. The best choice depends on what fish you keep (scaleless fish, loaches, catfish), whether you have shrimp/snails, and whether your tank can handle heat.

Option A: Heat + Time (no meds) - great for sensitive tanks

Heat speeds up the parasite's life cycle so it reaches the vulnerable free-swimming stage faster. This can work really well if your fish tolerate warmer temps and you keep oxygen high.

1. Raise temperature gradually (about 1°F / 0.5°C every few hours) until you reach 82-86°F (28-30°C), depending on species tolerance.
2. Add extra aeration (airstone or strong surface ripple).
3. Hold that temp for 10-14 days, even if spots disappear earlier.
4. Do small-to-medium water changes every couple days and lightly vacuum the substrate.

Option B: Meds (the most reliable for many community tanks)

If I want a straightforward win, I use an ich medication with a proven track record (often malachite green + formalin mixes, or other labeled ich remedies). Follow the label like you're baking-dose and timing matter.

• Remove activated carbon and Purigen (or expect the med to vanish).
• Keep lights dim-some meds are light-sensitive and fish are less jumpy.
• Over-aerate the tank during treatment.
• Dose for the full course, then keep treating a few days after the last visible spot (or follow label instructions if they're longer).

Option C: Salt (works, but know your livestock)

Aquarium salt can help with ich in some cases, and it's cheap. But it's not a universal fix-some plants, snails, and certain fish really dislike salt. I think of salt as a tool, not a lifestyle.

• Use plain aquarium salt (not table salt with additives).
• Dissolve it in tank water before adding-don't dump crystals on fish/plants.
• Dose carefully and track exactly how much you add, because only water changes remove it.
• If your tank has salt-sensitive stock (many plants, some catfish, most snails), skip this and use heat or a safe med instead.

My Go-To Ich Treatment Workflow (simple and effective)

If you want a no-drama routine that works for most tropical community tanks, this is what I do. Adjust based on what you keep, but the structure stays the same.

1. Day 1: Big water change (30-50%), clean prefilter sponge if you have one, remove carbon, boost aeration.
2. Day 1: Start chosen treatment (heat method OR a labeled ich med-don't shotgun multiple meds).
3. Days 2-7: Keep dosing on schedule or keep temp steady; do small water changes as recommended (some meds want redosing after water changes).
4. Days 7-14: Continue treatment past the last visible spot. This is where most people stop too early.
5. End: Run fresh activated carbon for 24-48 hours (optional) to clear medication, then remove it again.
6. End: Do a couple of extra water changes over the next week and keep watching fish closely.

Special Situations (shrimp tanks, planted tanks, and sensitive fish)

If you have shrimp or snails

A lot of ich medications are not invert-safe. If the tank is a shrimp tank (or you really care about your nerites/mystery snails), I lean toward heat (if livestock allows) or moving fish to a separate treatment tank.

• Treat fish in a hospital tank with meds, keep inverts in the display.
• Or use heat in the display tank if everyone tolerates it.
• Avoid copper unless you're intentionally treating in a separate bare tank and understand the risks.

Heavily planted tanks

Plants can react to both heat and certain meds. I've had some fine-leaved plants melt back at higher temps, and some meds discolor mosses. Usually the plants recover if you don't keep them cooking for ages.

• Aim for the lower end of the heat range if your fish allow it.
• Increase aeration-warm planted tanks can swing low on oxygen at night.
• If you medicate, watch for plant stress and keep the photoperiod moderate.

Scaleless and "delicate" fish

Loaches, some catfish, and a few other scaleless fish can get hammered by strong meds. For those tanks, I either use a medication that specifically calls out scaleless safety, or I go the heat route with heavy aeration.

What Not to Do (common mistakes I see all the time)

• Stopping treatment the moment spots disappear
• Using three different medicines because you're scared (this often stresses fish more than ich does)
• Cranking the heater to max in one jump (temperature shock is real)
• Forgetting oxygen (warm water + meds + stressed fish = gasping at the surface)
• Leaving activated carbon in while dosing and wondering why nothing changes
• Skipping water testing-ammonia poisoning can look like "sudden illness" and makes ich worse

How Long Until Fish Look Better?

With a good plan, you'll often see fewer new spots within a few days. Existing spots can hang around while the parasite finishes that protected stage. Breathing and flashing usually improve first if you're on the right track.

• 24-48 hours: less flashing in mild cases (not always)
• 3-5 days: fewer new spots appearing
• 7-14 days: typical full clear time depending on temperature and treatment

Aftercare: Getting the Tank Back to Normal

Once you're confident it's gone, don't just flip everything back in one hour. Fish are coming off a rough couple of weeks.

1. If you used heat, bring temperature down slowly over a couple days.
2. Do a couple of extra water changes across the next week to dilute leftover med/salt and refresh minerals.
3. Put carbon back only if you actually want to run it long-term (many tanks don't need it).
4. Watch for secondary issues: frayed fins, bacterial infections, or weight loss from not eating.

Preventing Ich From Coming Back

Ich usually enters your tank on new fish, plants, or shared gear. It turns into an outbreak when fish are stressed or water quality slips. Prevention is mostly boring habits-and boring habits work.

Quarantine (the best "medicine" you'll ever buy)

A simple quarantine tank saves you so much trouble. A spare 10-20 gallon, heater, sponge filter, and a couple hiding spots is enough. New fish spend a couple weeks there so you can watch them, feed them up, and treat without nuking your display tank.

• Quarantine new fish for 2-4 weeks if you can
• Use separate nets and siphons (or disinfect between tanks)
• Keep quarantine water stable and clean-stress in quarantine defeats the point

Keep stress low in the main tank

• Avoid temperature swings (a reliable heater is worth it)
• Don't overstock or let aggression simmer
• Do consistent water changes (whatever schedule you can actually stick to)
• Acclimate new fish slowly and keep lights low on introduction day
• Skip sudden big changes to scape, flow, or parameters unless you have to

Troubleshooting: If Treatment Isn't Working

If you're a week in and things look the same (or worse), something's off. Here's the checklist I run through.

• Are you sure it's ich and not velvet or something else?
• Did you remove carbon/chemical media?
• Are you dosing the true tank volume (subtract substrate/decor; many tanks hold less than the label size)?
• Did you miss doses or stop early when spots faded?
• Is the temperature stable (heater working, no big day/night swings)?
• Is oxygen high enough (fish gasping = fix aeration first)?
• Are ammonia or nitrite showing up (even small amounts can stall recovery)?

Quick Reference: A Simple Ich Plan You Can Follow

1. Confirm symptoms, test water, do a 30-50% water change.
2. Remove carbon/chemical media, add extra aeration.
3. Choose ONE: heat method (82-86°F / 28-30°C) for 10-14 days OR a labeled ich medication on schedule.
4. Light vacuuming + small water changes through the process.
5. Continue several days past the last visible spot.
6. Afterward: gradual return to normal temp, extra water changes, observe closely.

If you tell me your tank size, stocking (especially loaches/catfish/inverts), current temp, and what you have on hand (heater, air pump, meds), I can suggest which route I'd personally take and how I'd dose/schedule it.