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were measured in fish culture and hydroponic culture once a week at two times, morning (9:00 a.m.) and afternoon (3:00 p.m.). The fish biomass production was not different in any treatment (p > 0.05) and the total plant yield was greater (p < 0.05) in PAK than in COR. For the hydroponic culture in the a.m., the PO4 in PAK than in COR. The PAK treatment demonstrated higher food production and water treatment efficiency than the other two treatments.

This study compares the aquaponics Nile tilapia (Oreochromis niloticus)-pak choi (Brassica chinensis) system with and without a bacterial biofilter (BF and NBF) in a tropical location. The aim was to determine whether a semi-intensive aquaponics system NBF could offer a production alternative for small-scale farmers in this region, both technically and biologically. The Tilapia aquaponics culture was continuously recirculated and water was added (influent) and removed (effluent) from the plant aquaponics culture every 24 h. Total ammonia nitrogen (TAN) and nitrite nitrogen (NO 2 − -N) were analysed in the plant aquaponics culture influent and effluent. At the end of the experiment the individual fresh total weight, dry total weight, edible weight, height and diameter of the pak choi plants were measured. None of the pak choi variables showed significant differences between treatments. TAN and NO 2 − -N were higher in the NBF influent than in the BF influent. TAN and NO 2 − -N in the effluent of both treatments were similar and lower than in the influent. The plant aquaponics culture therefore works as a biofilter and the NBF aquaponics system could be used for small-scale farmers in the tropics, with easier management and less costs than a BF aquaponics system.