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A firefish that refuses food is one of the most common concerns for reef keepers, but it is not always a sign of a serious problem. New firefish commonly hide and refuse food for 24-72 hours while acclimating to a new tank. If the fish is newly introduced, give it time. If an established firefish suddenly stops eating, work through the causes below systematically.
New Fish - Normal Acclimation Behavior
Newly introduced firefish frequently hide in bolt holes and refuse food for 24-72 hours, and sometimes up to a week. This is normal acclimation behavior. The fish is stressed from transport and introduction to a new environment. Broadcast frozen mysis into the current near the fish's chosen bolt hole - firefish will often dart out to grab food even when still shy. Do not attempt to force-feed or disturb the fish during this period. If the fish is not eating after 7-10 days, investigate further.
Water Quality Problems
Poor water quality is one of the most common causes of appetite loss in established fish. Test water parameters immediately if a firefish that was eating well suddenly stops.
- Ammonia or nitrite above 0 ppm: Toxic to fish. Perform an immediate water change and identify the source.
- Nitrate above 20 ppm: Elevated nitrate suppresses appetite and immune function over time.
- Salinity instability: Rapid salinity changes stress fish and suppress appetite. Use an auto top-off system to maintain stable salinity. See our Best Auto Top-Off Systems guide.
- Temperature fluctuation: Sudden temperature changes stress fish. Maintain 72-78F consistently.
See our Best Reef Test Kits guide.
Aggression from Tankmates
A firefish being chased or harassed by aggressive tankmates will hide, stop eating, and eventually jump. Check for aggression from damselfish, dottybacks, large wrasses, or other territorial fish. If aggression is occurring, remove the aggressive fish or rehome the firefish. A stressed firefish that cannot come out to feed will decline quickly. See our Firefish Tankmates guide.
Insufficient Bolt Holes
Firefish without adequate bolt holes - small caves or crevices in the rockwork they can instantly retreat into when startled - experience chronic stress and may refuse to come out to feed. Ensure the tank has enough live rock with bolt holes distributed throughout. A firefish that feels exposed will not forage confidently. See our Best Live Rock and Reef Rock guide.
Disease
Loss of appetite is a common symptom of marine ich, velvet, and bacterial infections. Inspect the fish carefully for white spots, gold dust, fin damage, or abnormal breathing. If disease symptoms are present, move the fish to a hospital tank for treatment. See our Firefish Diseases guide.
Wrong Food or Food Size
Firefish have small mouths and may refuse food that is too large. Ensure food is appropriately sized - small frozen mysis, small pellets, or finely chopped frozen foods. Try different foods if the fish is refusing one type. Frozen mysis is the most reliably accepted food for firefish. See our Firefish Feeding Guide.
Lighting Changes
Sudden lighting changes can startle firefish and cause temporary hiding. Firefish are sensitive to abrupt light transitions. If the tank recently had a lighting change, give the fish a few days to adjust.
What to Do If Your Firefish Is Not Eating
- If newly introduced - wait 3-7 days and try broadcasting mysis near the bolt hole
- Test water parameters - ammonia, nitrite, nitrate, salinity, temperature
- Check for aggression from tankmates
- Inspect the fish for disease symptoms
- Try different foods - mysis, pellets, brine shrimp, copepods
- Ensure adequate bolt holes in the rockwork
- If no improvement after 10-14 days, consider moving to a hospital tank for observation