Page 306 - Trends in Science and Technology fo Sustainable Living

Trends in Science and Technology 267
for Sustainable Living

more work. Because basil and pak choy contain more nitrogen than
lettuce or coriander, the balance between fish feeding and plant
density may need to be adjusted correspondingly (Hambrey et al.,
2013).
Although many fish can be farmed at great density in tanks
in recirculated aquaculture or aquaponic systems, Tilapia (typically
Oreochromis niloticus) is the favored species for tropical and
subtropical environments. This is due to its ease of reproduction,
tolerance of low Dissolved Oxygen (DO) levels (0.2 ppm), high Total
Nitrate levels (>400 ppm), high Total Ammonia Nitrogen levels
(>90 ppm @ pH 6.0), and low pH levels (5.0) (Hambrey et al., 2013).
However, it should be noted that this species, like most others,
demands DO >6ppm, pH >6, and low ammonia and nitrite levels for
maximum growth and health (Hambrey et al., 2013).
In the variety of approaches used to raise them in captivity,
Tilapia are exceptional. The following are examples of commercial
operations: ponds, cages, raceways, tanks, net pens, lake ranching,
freshwater, brackish water, seawater, aquaponics, plastic drums, and
computer-controlled intensive recirculation systems. Production of
this fish variety is higher than any other farmed fish. Production of
Tilapia in metropolitan areas, high latitude regions, and even on
the International Space Station has been made possible by using
recirculating systems (Fitzsimmons, 2000, 2005).
One of the most significant fish species used in investigations
on substitute ingredients has proven to be Tilapia. The most typical
objective is to switch out fish meal and fish oils. Even though they
are typically reasonably small elements in tilapia diets, farmers
and researchers still wish to use locally available items and
further minimize the amount of fish products in the diet (Zerai, B.,
Fitzsimmons, K.M., Collier, R.J., & Duff, G., 2008).
Another advantage that Tilapia have over many other
common aquaculture species is their capacity to thrive in biofloc
systems. According to Avnimelech (2009 and this volume), Tilapia
are especially suited to flourish in biofloc conditions that would
stress most other fish. This low-cost approach for growing healthy