Significant factors affecting the economic sustainability of closed aquaponic systems. Part II: fish and plant growth

Autor:
Palm, Harry W.; Bissa K.; Knaus, U. 2014
In:

AACL Bioflux

Bandangabe: 7
Auflage: 3
Ergaenzung: http://www.bioflux.com.ro/aacl
ISBN: 1844-9166
Seite: 162 - 175
Jahr: 2014

Einordung:
Institut: Professur Aquakultur und Sea-Ranching

Abstract:
Two identical closed ebb-flow substrate aquaponic systems for warm-water fish were tested
for fish and plant productivity. Each system contained 3.7 m3 water, and the relationship of the water
volume in the aquaculture tank to the settling basin (sedimenter, clarifier), the biofilter and the
hydroponic units was 2.25:1:0.075:0.6 (fish tank:hydroponic unit = 3.75). The comparative batch
cultivation of African catfish (Clarias gariepinus) and Nile tilapia (Oreochromis niloticus) at the fish feed
input level of 200 g per day resulted in non-significant total growth of 13 kg. The feed conversion ratios
(FCR) were 1.0, better values compared with earlier tested closed aquaponic systems. The specific
growth ratio was not significantly different (p < 0.05) between C. gariepinus (0.65% d-1 ± 0.25) and O.
niloticus (0.71% d-1 ± 0.19). Combined dissolved oxygen (DO) levels in the fish tank, clarifier and sump
were significantly different between the two species, with 6.95 mg L-1 (± 0.50) in C. gariepinus and 4.73
mg L-1 (± 1.05) in O. niloticus. Significantly better growth was observed for plants in combination with
the Nile tilapia, with 55.89 g (± 49.77) for lettuce and 168.27 g (± 350.88) for cucumber fruits. This is
referred to a slightly different light regime and a different fish species cultivation. The available plant
nutrients (nitrite, nitrate), as well as the suspended particle load, in both identical systems, also differed,
with consequences for system maintenance and substrate biofilter activity.
Key Words: African catfish, aquaponics, biomass weight gain, Clarias gariepinus, ebb and flow system,
fish to plant combination, Tilapia.

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Letzte Änderung des Eintrages: 01.02.2017

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