Acta Univ. Agric. Silvic. Mendelianae Brun. 2017, 65, 441-446

https://doi.org/10.11118/actaun201765020441
Published online 2017-04-30

The Addition of Simple Biological Filters of Different Capacity to Semi‑Recirculating Fish Rearing System and Its Effects

Štěpán Lang

Department of Zoology, Fisheries, Hydrobiology and Apiculture, Faculty of AgriSciences, Mendel University in Brno, Zemědělská 1, 613 00 Brno, Czech Republic

Aquaculture is currently one of the fastest growing food-producing sectors, accounting for around 50 % of the world’s food fish production. Limited resources, together with climatic change, have stimulated the search for solutions to support and sustain the production of fish as a source of protein for human consumption. The integration of a biological filtration (BF) into a semi-recirculating fish rearing system can increase its carrying capacity and increase system efficiency compared to its’ energy consumption with minimum changes of system composition and minimal costs. Question is the capacity of the BF installed to a system and how it affects water quality. Two different amounts of BF media (surface) added to semi-recirculating rearing system compared with the same system without BF were tested in case of this study. The results have shown that if the BF capacity is insufficient, BF can have negative effects to the quality of water environment. The insufficient amount of BF media caused 4 times reduction of ammonia nitrogen (N-NH4+) in system with BF compared to non BF system so it increased the system capacity for feed load 4 times. On the other hand it also increased nitrite nitrogen concentrations permanently more than 5.8 times for BF system compared to non BF system and increased rearing costs because the need of adding chlorides to the system to protect fish from nitrites toxicity. When the BF was dimensioned properly (next year) there were almost no N-NH4+ in a system (0.10 mg.l−1) and the concentration of N-NO2 was kept at low levels too (0.150 mg .l−1). The nitrates (N‑NO3) concentration reached the level of 5.37 and 8.65 mg.l−1 in 2012 and 2013 respectively.

Funding

This research was financially supported by National Agency for Agriculture Research (NAZV) number QJ1210013: Technology of fresh water fish breeding with use of Danish recirculation technology with aim to effective environment management and veterinary care.

References

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