Do Ocean Fish Sleep?

Yes, fish sleep—but differently than humans. Lacking eyelids, they don't close eyes, but exhibit sleep states:

• Sleep Stages: Some species (parrotfish, zebrafish) show NREM and REM cycles.
• Duration: Varies widely—ocellated wrasse ~8 hours/day; damselfish minutes at a time.
• Postures/Locations: Hovering mid-water, resting on bottom, hiding in crevices.
• Functions: Energy conservation, cellular repair, cognitive maintenance, predator avoidance.

Research continues; sleep patterns differ across 30,000+ fish species.