Quarantine Tank Setup
40-gallon minimum (flowerhorns even 4 inches need space). Bare bottom. Sponge filter pre-cycled in main tank.
Heater at 80°F. Single dim light. Hiding spot (large PVC pipe or upside-down clay pot).
Days 1-7 — Observation
No medication. Just observe daily for: clamped fins, white spots, hole-in-head pits, unusual breathing, refusal to eat.
Test water daily and do small water changes as needed. New fish are stressed — minimize disturbance.
- ✦Feed lightly — stressed fish should eat less.
- ✦Use a flashlight to check for early disease signs.
Days 8-14 — Prophylactic Treatment
Even if the fish looks fine, dose API General Cure (praziquantel + metronidazole) per package. This clears most internal and external parasites.
Continue treatment for 5-7 days. Do a 50% water change after treatment.
Acclimation to Main Tank
Float the fish in a bag of QT water in the main tank for 30 minutes. Add small amounts of main tank water every 5 minutes for 30 more minutes.
Net the fish out and release. Discard the bag water (do not pour into main tank).
Why It Matters
A single sick new fish can wipe out an established tank. With $200+ investments in display fish, the cost of quarantine setup pays for itself many times over.
Most experienced flowerhorn keepers maintain a permanent QT tank specifically for new arrivals.