Visual Inspection
Bright color, firm body, smooth scales, clear eyes.
Avoid: faded color, ragged fins, clamped fins, skinny belly, bulging eyes, white spots.
Behavior Check
Active swimming in mid-water. Responsive to environment.
Avoid: hiding in corners, swimming erratically, gasping at surface, loners away from school.
Store Tank Condition
Clean store tank suggests healthy stock. Cloudy, smelly, or dead-fish tanks are contaminated.
Ask when the tetras arrived — fish 7+ days in the store show existing issues; newly arrived fish may still be stressed.
Quarantine Regardless
Even healthy-looking tetras should quarantine 14-21 days. Many carry subclinical neon tetra disease.
Treat prophylactically with metronidazole in the quarantine tank.