Stressed fish lose color temporarily. Common in newly-added fish. Fades back after 1-2 weeks of stable conditions.
Single-food pellet diet leads to color loss. Rotate frozen mysis, brine shrimp, color-enhancing foods (NLS Thera+A, spirulina, krill).
Fish lose color as they age. Normal after 50%+ of expected lifespan.
Bullied fish lose color. Watch behavior and separate aggressor.
HLLE (head and lateral line erosion), early bacterial infection. Check for pits or fin damage.
Test water first - many "behavior" issues are actually water-quality problems. Use the water parameter checker to score your test results, the disease symptom matcher if you observe physical signs, or the general diagnoser to narrow further. Browse the full disease database if illness is suspected.
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