Copper quarantine can save your display tank. It stops many common parasites fast. It also harms fish when dosed wrong.
This guide explains how to dose copper safely. You will learn targets, testing, and timing. You will also learn common mistakes to avoid.
Set up a copper-safe quarantine tank
Use a bare-bottom tank for copper treatment. A 10 to 20 gallon tank works for most fish. Use a heater, lid, and an air stone.
Add a sponge filter seeded in your sump for 2 to 4 weeks. This helps prevent ammonia spikes. Keep salinity stable at 1.025 specific gravity. Keep temperature at 77 to 79°F.
Remove anything that binds copper. Do not use live rock, sand, or rubble. Avoid carbon and phosphate media during treatment. Use PVC elbows for shelter instead.
Plan for daily observation and testing. Copper is not a “set and forget” medication. If you need a full workflow, see our quarantine tank setup guide.
- Ammonia target: 0.0 ppm, with alerts at 0.25 ppm
- pH target: 8.0 to 8.3, avoid swings over 0.2 per day
- Oxygen: strong surface agitation and steady bubbles
Choose a copper type and hit the right therapeutic range
Use only one copper product at a time. Copper power and CopperSafe are chelated copper. Cupramine is amine-complexed copper. Each has a different test method and target range.
Follow the manufacturer’s target range exactly. As a practical rule, many chelated products run near 1.5 to 2.5 ppm. Many ionic products run near 0.15 to 0.25 ppm. Do not mix these scales.
Raise copper slowly over 48 hours for sensitive fish. Angels, butterflies, and wrasses often handle slow ramps better. Start at 25% dose on day one. Move to 50% after 12 hours. Reach 100% by day two.
Always test with a kit that matches your copper type. Many hobbyists use Hanna or Seachem kits. Test twice daily during the ramp. Test daily once stable. For disease timelines, see our marine ich treatment overview.
- Measure real water volume, not tank size. Subtract gear and headspace.
- Dose into high flow. Wait 30 minutes, then test again.
- Log results with time, dose amount, and test reading.
Maintain copper for 14 days and manage problems
Hold therapeutic copper for a full 14 consecutive days. Start counting only after you reach the target. Missing a day can reset the clock. Parasites can rebound fast.
Water changes lower copper. Re-dose after each change based on replaced volume. Example: you change 5 gallons in a 20 gallon system. That is 25% of the water. Add 25% of the original copper dose, then test.
Watch fish behavior closely. Fast breathing can mean low oxygen or high copper. Loss of appetite can mean stress or ammonia. Add extra aeration first. Then confirm copper level with a second test.
Ammonia is the top copper quarantine killer. Use an ammonia badge plus liquid tests. If ammonia hits 0.25 ppm, do a water change at once. Add a detoxifier only if your copper brand allows it. Some reducers can alter copper readings.
- Common mistake: using sand or rock. Copper will drop without warning.
- Common mistake: dosing by “capful.” Use a syringe or graduated cup.
- Troubleshooting: copper reads low daily. Check for carbon, pads, or calcareous media.
After day 14, remove copper with carbon and water changes. Run carbon for 48 hours and test until copper reads zero. Then observe fish for 7 to 14 more days. For next steps, read our fish quarantine protocol.
Sources: Humblefish Disease Forum copper protocols; Seachem Cupramine instructions; Mardel CopperSafe label directions; Hanna Instruments copper checker guidance.
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