The experimental integrated systems were operated with fish for 2 months prior to the initiation of trial 1 in order to acclimate the biofilters and establish a steady-state bacterial biomass in the biofilter so as to minimize net nutrient uptake by bacteria at the beginning of each trial. At the initiation of trial 1, systems were flushed and fingerling Nile tilapia (Oreochromis niloticus) having an average weight of 3.8 g were added to each system up to the treatment biomass. Due to our inability to obtain fish of similar size for trials 2 and 3, fish from the prior trial were pooled and reallocated to the integrated systems up to the treatment biomass for the following trial.