De Cheiro Da Norte Chilli
ratio of 1 m3 of fish rearing tank to
2 m3 of pea gravel 3 to 6 cm in diameter as hydroponic media is recommended for reciprocating (flood
and drain) gravel aquaponic systems. This ratio requires that tilapia
are raised to a final stocking density
of 60 kg/m3 and fed appropriately.
With the recommended ratio no
solids are removed from the system. The hydroponic beds should
be cultivated (stirred up) between
crops and inoculated with red
worms to help break down and assimilate the organic matter. With
this system nutrient supplementation may not be necessarily.
As a general guide for raft aquaponics, a ratio in the range of 60100 g of fish feed/m2 of plant growing area per day should be used.
Ratios within this range have been
used successfully in the UVI system
for the production of tilapia, lettuce, basil and several other plants.
In the UVI system all solids are removed, with a residence time of ˂1
day for settleable solids (>100 microns) removed by a clarifier, and 3
to 7 days for suspended solids removed by an orchard netting filter.
The system uses rainwater, and sup-
Candy Plum Tomato
plementation is required for potassium, calcium, and iron.
Pest and Disease Control:
Aquaponic systems are characterized by a broader range of microflora and -fauna than conventional
hydroponic systems, especially because the cultivation of fish and
biofiltration occurs in the same water loop. Conventional pesticides
that are used in hydroponics cannot
be used in aquaponics because of
toxicity risk to the fish and to the
desired biofilm (e.g., autotrophic
nitrifying biofilm). The need to
maintain the nitrification biofilm
and other nutrient solubilizing microorganisms also prevents the use
of antibiotics and fungicides for fish
pathogen control and removal in
the aquatic environment. Furthermore, antibiotics are not allowed
for plant application so their use
against fish pathogens must be
avoided in aquaponic systems.
These constraints demand innovative pest and disease management
solutions for fish and plants that
minimize impacts on fish and desired microorganisms. Plant and
fish pests and pathogens can be
divided into four different catego-
Malaga
ries based on specific alternative
treatment solutions. These are (1)
plant pests – mostly insects that
damage the leaves and roots (e.g.,
aphids, spider mites); (2) plant diseases – microorganisms (e.g., bacteria, fungi) and viruses that attack
plants; (3) fish parasites (e.g., monogenean, cestoda); and (4) fish diseases caused by viruses and microorganisms.
Rearing and crop practices that decrease the occurrence of diseases
could be applied such as preventative sanitary measures, low density
of fish and/or plants, and/or control
of environmental conditions, which
decrease relative humidity around
the plants. In addition to these
practices, a few innovative methods
of biological control already exist
for plants cultivated under field or
greenhouse conditions. These
methods are based on the use of
microorganisms with biocontrol
activity, or extracts of such microorganisms or extracts of plants
(including essential oils) that show
high antimicrobial efficiency and
short residence time.
Vegetable Selection:
Many types of vegetables have