All newly set-up aquariums must go through a filter conditioning process in order to sustain fish life (see our “New Tank Water Conditions” tip sheet). It will take the water approximately 4-6 weeks to condition, during which time only a small number of fish can be added to the tank. Once the aquarium has been set up and running for a minimum of 24 hours, six (6) 1.50 inch fish per 10 gallons of water can be safely introduced. Over the next several weeks when the water quality tests of Ammonia and Nitrite reach zero, more fish species can be added.