Aquarium Medication Dosing Calculator
Created by: Lucas Grant
Last updated:
Calculate accurate medication doses for treating fish diseases based on your actual water volume. Get adjusted doses for sensitive species like scaleless fish and invertebrates, plus re-dosing amounts after water changes during treatment.
Aquarium Medication Dosing Calculator
AquariumCalculate accurate medication doses for fish treatments based on actual water volume and species sensitivity
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What is an Aquarium Medication Dosing Calculator?
An Aquarium Medication Dosing Calculator helps determine the correct amount of fish medication based on your actual water volume. Accurate dosing is critical - too little medication won't treat the disease, while too much can stress or kill fish, especially sensitive species.
This calculator accounts for water displacement from decorations and substrate, adjusts for sensitive species, and provides dosing schedules for common aquarium medications.
Medication Dosing Guidelines
Actual Water Volume:
Actual Volume = Tank Volume - Displacement (typically 10-20%)
Sensitive Species:
Scaleless fish, invertebrates: Use 50-75% of normal dose
Re-dosing:
After water change: Re-dose only for new water volume
Common Aquarium Treatments
Ich/White Spot (Ichthyophthirius): Most common freshwater disease. Treat with copper-free ich medication or salt. Raise temperature to 82-86°F to speed parasite lifecycle. Continue 3-4 days after last spot disappears.
Bacterial Infections (Fin Rot, Columnaris): Treat with antibacterial medications like erythromycin or kanamycin. Improve water quality as primary intervention. May affect beneficial bacteria.
Fungal Infections: White cottony growths, often secondary to injury. Treat with antifungals like methylene blue or Pimafix. Remove affected decorations and improve water quality.
Parasites (Flukes, Worms): Treat with praziquantel for internal parasites. Usually requires 2 treatments spaced 2 weeks apart to kill hatched eggs. Safe for most scaleless fish.
Frequently Asked Questions
How do I calculate medication dose for my aquarium?
Medication dosing is based on actual water volume, not tank size. Subtract volume displaced by substrate, rocks, and decorations (typically 10-15%). Most medications specify dose per gallon or liter - never exceed recommended doses as many fish medications have narrow safety margins.
Should I treat the whole tank or use a quarantine tank?
Quarantine tanks are preferred for treating individual sick fish - smaller volume means less medication, and you avoid medicating healthy fish or crashing beneficial bacteria. Treat the main tank only for highly contagious diseases affecting multiple fish or when quarantine isn't possible.
Do I need to remove carbon from my filter when medicating?
Yes, activated carbon removes most medications from water, rendering treatment ineffective. Remove carbon before dosing and keep it out for the entire treatment duration. You can resume carbon filtration 24-48 hours after the final dose to help remove residual medication.
How do water changes affect medication dosing?
Water changes dilute medication concentration. After a water change during treatment, re-dose only for the volume of new water added. For example, a 25% water change on a tank being treated needs 25% of the original dose added back.
Can I combine multiple aquarium medications?
Generally no - combining medications can be toxic or reduce effectiveness. Never combine medications unless specifically stated as safe by the manufacturer. Complete one treatment course, do water changes, then start another medication if needed. Some salt treatments can be combined with certain meds.
What medications are unsafe for scaleless fish or invertebrates?
Copper-based medications are toxic to invertebrates and many scaleless fish (loaches, catfish). Malachite green and formalin require reduced doses for scaleless fish. Salt at treatment levels harms most freshwater invertebrates. Always check medication labels for species restrictions.
How long should I continue treatment after symptoms disappear?
Complete the full recommended treatment course even if fish appear recovered. Stopping early can allow resistant parasites or bacteria to survive and cause relapse. Most treatments are 7-14 days. Ich treatment should continue 3-4 days past last visible spot.
Why isn't the medication working on my fish?
Common reasons: wrong diagnosis (treating for wrong disease), medication degraded from age/heat/light, carbon still in filter removing medication, dose too low, or resistant strain. Ensure correct diagnosis, fresh medication, no carbon, accurate dosing, and complete treatment duration.
Sources and References
- Fish Disease: Diagnosis and Treatment, Edward Noga, Wiley-Blackwell, 2024
- Seachem Laboratories, Medication Dosing Guidelines, 2024