Top 5 Fish Medications and When to Use Them
Don’t wait until your fish are gasping for life to take action — these are the top meds every aquarist should keep in their arsenal, and exactly when to use them.
When something seems off in your aquarium — like flashing, white spots, or bloating — the wrong medication can do more harm than good. This post covers the five most effective over-the-counter fish treatments, with real-world guidance on symptoms, dosing, and quarantine tips.
🧪 Why You Shouldn’t Medicate Blindly
Before using any medication, it’s essential to diagnose the problem. Treating the wrong condition can stress fish, destroy your beneficial bacteria, and waste time.
Use this guide with our Diagnose Sick Fish Symptoms Guide and Fish Health Checklist to pinpoint the issue before medicating.
🥇 1. Seachem ParaGuard
- Best for: External parasites, fungus, mild bacterial infections
- Symptoms: Ich, velvet, flukes, mouth fungus, early fin rot
- Dosage: 5 mL per 10 gallons daily for up to 14 days
ParaGuard is a gentler alternative to copper or formalin, making it safe for most freshwater fish and tanks with sensitive plants.
- Remove carbon and UV filters before use
- Not effective for internal parasites
- Best used in a separate hospital tank
🔗 Related: Quarantine Tank Setup Guide
🥈 2. API General Cure (or Fin & Body + Expel-P)
- Best for: Internal parasites, protozoans
- Symptoms: Stringy poop, weight loss, scratching, bloating
- Dosage: 1 packet per 10 gallons; repeat every 48 hours (3x)
This combo targets both protozoan infections and internal worms. Use in quarantine tanks and consider medicated food for internal dosing.
- Combine with Seachem Focus for food binding
- Do not overdose
- Great for guppies, bettas, and community tanks
🔗 Related: Feeding Sick Fish Tips
🥉 3. Fritz Maracyn
- Best for: Bacterial infections (gram-positive)
- Symptoms: Fin rot, cotton mouth, popeye, ulcers
- Dosage: 1 packet per 10 gallons daily for 5 days
Maracyn is erythromycin-based and effective against early-stage bacterial infections, especially when caught quickly.
- Safe for in-tank use
- Replace carbon after treatment
- Combine with Maracyn 2 for broader protection
🔗 Related: Fin Rot Symptoms & Fixes
🔬 4. Ich-X by Hikari
- Best for: Ich, velvet, mild fungal infections
- Symptoms: White spots, dusty gold coating, surface rubbing
- Dosage: 5 mL per 10 gallons initially; partial redose daily
Ich-X combines malachite green and formalin for maximum impact against protozoa. Use carefully — it’s not shrimp-safe.
- Remove carbon and increase aeration
- Treat for 3–5 days after symptoms vanish
- Not for use with scaleless fish or inverts
🔗 Related: Ich Prevention Best Practices
💊 5. Seachem Kanaplex
- Best for: Internal bacterial infections, dropsy, popeye
- Symptoms: Pineconing, cloudy eyes, bloating, lethargy
- Dosage: 1 scoop per 5 gallons every 2 days (3x)
Kanaplex treats systemic bacterial issues and is one of the few meds that works when absorbed via food or gills. Use with Focus to bind to food.
- Combine with Metroplex for deep infections
- Watch ammonia levels
- Use in quarantine if fish is visibly bloated
🔗 Related: Dropsy Diagnosis & Management
⚠️ Medication Safety and Quarantine Tips
- Always quarantine sick or new fish to avoid contaminating the main tank
- Remove carbon and UV sterilizers during treatment
- Use an air stone to boost oxygen during medication
- Monitor water quality, especially ammonia and nitrites
When in doubt, test your water first. Many illnesses stem from poor conditions, not disease.
🧰 Medication Cabinet Checklist
| Medication | Use For |
|---|---|
| ParaGuard | External parasites, fungus |
| General Cure | Internal parasites |
| Maracyn | Bacterial infections |
| Ich-X | Ich, velvet, fungus |
| Kanaplex | Internal bacterial issues |
🧠 Final Thoughts
The key to saving your fish isn’t in your medication drawer — it’s in early detection and accurate diagnosis. Treat the illness, not just the symptoms.
- Don’t medicate without identifying the problem
- Use a quarantine tank whenever possible
- Always test water before and during treatment
🔗 Start here: Diagnose Sick Fish Symptoms Guide
📄 Download this as a printable Fish Health Checklist
🐠 What’s Next?
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