Buy medications before you need them. Ich progresses through its life cycle in 4–7 days at 78°F. Velvet can kill in 7–14 days untreated. Shipping takes 2–7 days. If you wait until the fish shows symptoms to order medication, you may be treating an advanced case instead of an early one.
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The core six
| Medication | Treats | Form | Notes |
|---|---|---|---|
| Seachem Prime | Ammonia detox, chloramine removal | Liquid | Buy this first; use at every water change |
| Seachem KanaPlex | Gram-negative bacterial disease | Powder | Fin rot (moderate/severe), popeye, septicemia |
| Hikari Ich-X | Ich, velvet | Liquid | First-choice for both protozoan parasites |
| API Furan-2 | Bacterial disease (nitrofurazone) | Powder packets | Severe fin rot, columnaris; combine with KanaPlex for worst cases |
| API General Cure | Internal parasites, HITH, hole-in-head | Powder packets | Contains metronidazole + praziquantel |
| Epsom salt (Magnesium sulfate) | Osmotic support | Granules | Popeye, constipation, bloat; not a cure alone |
1. Seachem Prime
The water conditioner that covers more emergencies than anything in this list.
Prime dechlorinates and dechloramines tap water for use in water changes. Beyond that: it detoxifies ammonia, nitrite, and nitrate for 24–48 hours, making them temporarily non-toxic to fish while the nitrogen cycle processes them. In any water quality emergency — new tank cycling, ammonia spike after medication crashed the cycle, overdue water change — Prime is the first response.
Dose: 1 cap (5 ml) per 50 US gallons for standard use. Double dose (2 caps per 50 gallons) for emergency detox. Safe at 5× normal dose.
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2. Seachem KanaPlex (kanamycin)
The first-line antibiotic for gram-negative bacterial disease in bettas.
Covers: fin rot (moderate and severe), popeye (exophthalmia), septicemia (red streaks), and most bacterial infections caused by Aeromonas and Pseudomonas — the two most common opportunistic pathogens in betta tanks.
Can be dosed in tank water or mixed with food (using Seachem Focus as a binder). Food dosing is more effective for systemic infections because the antibiotic is delivered directly to the bloodstream rather than absorbed through the gills and skin.
Does not affect biological filtration significantly at therapeutic doses — one of KanaPlex’s advantages over nitrofurazone-based medications.
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3. Hikari Ich-X
The current standard of care for ich and velvet.
Active ingredients: malachite green and formalin at therapeutic concentrations. Effective against Ichthyophthirius multifiliis (ich) and Piscinoodinium pillulare (velvet). Also labeled for other external protozoan parasites.
Dose: 5 ml per 10 gallons, daily, with a 25% water change before each redose. Run for 10–14 days minimum — ich and velvet have life cycles that must complete before the parasite is eliminated.
For velvet specifically: combine Ich-X with complete darkness (cover the tank) for the duration of treatment to block the parasite’s photosynthesis.
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4. API Furan-2 (nitrofurazone)
The second-tier bacterial antibiotic for cases that require more firepower than KanaPlex alone, or that show columnaris (which responds better to nitrofurazone than kanamycin in some strains).
Furan-2 does kill biological filtration. Treat in a hospital tank, not the main display.
The most effective protocol for severe fin rot or septicemia is KanaPlex + Furan-2 combined — hitting gram-negative bacteria with two different mechanisms simultaneously. See fin rot for the dosing protocol.
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5. API General Cure (metronidazole + praziquantel)
Covers internal parasites and hole-in-the-head disease.
Metronidazole targets flagellate protozoa (Hexamita, causing hole-in-head disease) and some anaerobic bacteria. Praziquantel covers trematodes (flukes) and cestodes. The combination makes API General Cure a useful catch-all for internal parasite presentations.
Also effective for betta constipation when dietary modification alone is insufficient — metronidazole has limited use here but the praziquantel addresses any parasitic component.
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6. Epsom salt (magnesium sulfate)
Not a disease treatment on its own, but an essential osmotic support tool.
Popeye: 1 teaspoon per gallon in the hospital tank reduces fluid pressure behind the affected eye while antibiotics address the infection. See popeye treatment.
Constipation and bloat: 1/4 teaspoon per gallon acts as a mild laxative by drawing fluid into the intestinal tract. Use after a 2–3 day fast, alongside daphnia feeding.
Standard pharmacy Epsom salt (unscented, no additives) is identical to aquarium-branded versions at 1/10th the price. Buy it at a pharmacy.
What to avoid
Melafix / Bettafix — tea tree oil, irritates the betta labyrinth organ. Neither treats bacterial disease effectively. Do not use.
Aquarium salt as a treatment for everything — aquarium salt (sodium chloride) has limited legitimate use as an adjunct in mild fin rot treatment (1 tbsp per 5 gallons, 7–10 days). It does not treat ich, velvet, bacterial infection, or internal parasites. It is not a substitute for any of the medications above.
Broad-spectrum “cure-all” products — medications marketed to treat “all fish diseases” typically contain inadequate concentrations of active ingredients and encourage guessing a diagnosis rather than confirming it. Treat specifically.
Expired medications — check dates. Degraded malachite green (in Ich-X) breaks down to less effective compounds. Degraded nitrofurazone loses potency. Date your bottles when you open them.
Storage
Keep all medications in a cool, dark location — a cabinet away from the tank (heat and light degrade liquid medications faster). Powder medications (KanaPlex, API Furan-2) last longer than liquids after opening. Epsom salt lasts indefinitely if kept dry.
A basic disease kit in a shoebox under the tank stand takes 30 seconds to access when you need it.
Related on this site
- The Disease Guide: Diagnosis Before Treatment
- Quarantine Tank Setup: Where You Treat
- Fin Rot: Medication Protocol
- Ich: Heat and Ich-X Protocol
- Velvet: Darkness and Copper Protocol
- Popeye: Kanamycin and Epsom Salt
- Septicemia: Red Streaks and the Treatment Window
- Best Water Test Kits
Frequently asked
- What is the most important medication for a betta keeper?
- Seachem Prime water conditioner, while not a medication in the traditional sense, handles more emergency situations than anything else — it detoxifies ammonia instantly for 24–48 hours while you correct a water quality failure. After that, Seachem KanaPlex (kanamycin) for bacterial disease and Hikari Ich-X for ich and velvet are the two treatments that cover the most common disease presentations.
- Should I use Melafix or Bettafix for bettas?
- No. Both contain tea tree oil (Melaleuca), which irritates the labyrinth organ in bettas and other anabantoids. They are marketed as mild treatments for fin damage and bacterial disease. They are ineffective at the concentrations used and actively harmful to bettas. Do not use them.
- Can I use Ich-X for velvet?
- Yes. Hikari Ich-X is labeled for both ich and velvet. Both are protozoan parasites vulnerable to malachite green, the active ingredient. The velvet treatment protocol additionally requires complete darkness (to block the parasite's photosynthesis) and mild heat elevation.
- How long do betta medications last once opened?
- Most liquid medications: 1–2 years if stored in a cool, dark location. KanaPlex powder: 2–3 years sealed, 1 year once opened. Always check the expiration date before treating; degraded medication can be ineffective or harmful. Store away from direct sunlight and heat.
- Do I need a separate hospital tank to medicate?
- Yes. Medicating the main display tank kills biological filtration, harms invertebrates (copper kills shrimp; kanamycin kills snails), and makes it impossible to remove medication quickly if the fish reacts badly. A bare 2.5–5 gallon hospital tank with a pre-seeded sponge filter is essential. See the quarantine tank guide for setup.