Abstract
Aquaponics is an offshoot of aquaculture which torches on central issues of great concern to the world of
today in many respects. These central issues are organic food production and environmental
sustainability. What role can be played in aquaculture towards addressing the present world demand on
organic food production and environmental sustainability forms the frame on which the present study is
founded. Aquaponics is understood as a system by which two important production systems
(aquaculture and hydroponics) integrate with the mediation of microorganisms (bacteria) to yield
produce equitable to either systems or a multitude. In so doing, fish production is multiplied anp
organically produced vegetables are obtained. The tilapia mostly adopted for aquaponics throughout the
world again has the potential aptitude to compete with the carps in the near future due to its low trophic
level, particularly in the developing African continent. Then, multiple fish production in aquaponics
means increasing (quality) food production effort. Organic vegetable production means replacement of
chemical fertilizers used for hydroponics vegetable production, hence fostering sustainable healthy food
produce. Environmental pollution is mitigated by use of the pollution-prone aquaculture wastes for
vegetable production, hence featuring sustainability. As a closed recirculation system, aquaponics allows
for water re-use, and the valuable water resource is conserved hence featuring sustainability. As a soilless
agricultural system, aquaponics systems are manifested in a variety of production methods such as on the
walls, rooftops, towers erected with Poly vinyl pipes, therefore maximizing the use of space and the illeffect of non-arable land is subjugated. The treatment factor of the research was the fish feed. The protein
contents proportion in feed ingredients were strategically varied, viz: 15, 25, 35 and 32%, representing experimental treatments T1, T2, T3 and T4 (control). This formed the bases for evaluation of the study
objectives. All the treatments were made in triplicates and except for experiment 3, all were located
within the semi-closed laboratory shade. Genetically Improved Farmed Tilapia (GIFT) juveniles
(Oreochromis niloticus) were used in all the experiments. The stocking density for all the treatments was
1.0-2.0kg with number ranges of 19-127 fish juveniles in 200L water volume; while 6 seedlings each for
okra and tomato, 12 for amaranth were grown in media-beds of 0.49 m² area. The objectives in the three
experiments were concerned with the changes in growth of tilapia, also the growth and production
performance of okra, tomato and amaranths with varying treatments protein content; while the fourth
objective concerned the economic potentials of aquaponics with tilapia and the three vegetables. In the
fourth experiment, the entire gadget for all experiments was evaluated and translated into an outdoor
model aquaponics facility. The physico-chemical parameters making up the water quality, viz: Temp.
('C), pH, Dissolved Oxygen (DO), Ammonia (NH3), Nitrites (NO2) and Nitrates (No3) in mg/1; were
closely monitored using thermometers, pH meters, D0 meters and Laboratory test kits of proven
standards. Reduced values of NH3 and NO3 in the fish tank (effluent) indicate high crop-utilization of
fertilizer resulting from nitrification processes. Results generally indicate the growth performance of O.
niloticus linked to other factors than increased protein levels in aquaponics. Tilapia production (kg/m³)
with okra was 3.5, 3.75, 5.74, 5.34 (T1, T2, T3, T4); with tomato was 13.23, 9.8, 12.41, 14.35 (T1-T4); with
amaranths was 7.18, 8.15, 7.01, 2.94 (T1,T2, T3 and T4). Okra production was 4.06, 2.43, 4.39 and 4.67
kg/m² for T1, T2, T3 & T4.; tomato 5.88, 4.19, 10.26, and 15.0 and amaranths 0.80, 1.05, 2.0, 1.59 kg/m²
respectively. The studies found the elements of Potassium in Bangladeshi (baked bricks) gravels in
reasonable quantities. The fourth experiment results reveal the Benefit-Cost-Ratio (BCR) for laboratory
aquaponics as 0.08 and 1.6 for the outdoor model aquaponics facility. In conclusion, a BCR less than '1'
means investment option generates losses and a BCR greater than '1 means investment option generates
profit. As tilapia growth is linked to other factors than increased protein levels, 15% protein level suffices
for economic production of the fish. The kg/m² production of okra and tomato in aquaponics may be
increased by locating the vegetable beds outdoors. Loss of greenish color in aquaponics with tilapia-okra
and tilapia-tomato production reveal the lack of Iron and Calcium in the system as suggested in literature
since the third essential element (Potassium) occur in the Bangladeshi gravel.