Zoanthids (Zoanthus spp.) lifespan in home aquariums is indefinite on average. Factors that extend lifespan: stable water parameters (no daily swings), high-quality varied diet, peaceful tankmates, adequate tank size (minimum 10 gallons), and quarantine of new tankmates. Factors that shorten lifespan: water-quality crashes (ammonia spikes), aggressive tankmates, overcrowding, single-food diet, and chronic disease that goes untreated. Zoanthids kept in mature established tanks (6+ months old) live closer to the upper end of the range; recently-set-up tanks see higher mortality. Captive-bred specimens typically outlive wild-caught counterparts because they were raised on aquarium parameters from juveniles.
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