When Can I Add Fish to a New Reef Tank?

Wait until ammonia and nitrite test zero for at least several days after the cycle completes. Salinity and temperature should already be stable. First fish should be hardy, reef-safe species appropriate for your tank size — clowns, some gobies, or a single tang only if the tank is large enough for adults.

Add one or two fish, then wait two to three weeks before the next addition. Each fish increases bioload and can stress the cycle if you rush.

Acclimate slowly with temperature float and drip-style water mixing. Record introduction dates in ReefDiary livestock so you connect future ich outbreaks to a specific shipment.