• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.378-387
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• 2017

This study was performed to isolate bacteria that could control the nitrite levels in a biofloc technology (BFT) culture tank. Nitrite-eliminating bacteria were isolated from a BFT culture tank rearing goldfish, and the isolated bacterium exhibiting the most potent nitrite eliminating ability was labeled as the "NOBSB1" strain. Sequencing the 16S rRNA revealed that NOBSB1 is a species in the genera Bosea. NOBSB1 had the following characteristics with regard to nitrite removal: (1) it removed nitrite by functioning heterotrophically in the presence of a carbon source (sugars); (2) it eliminated nitrite most effectively within a temperature range of $20-30^{\circ}C$, but its activity decreased at temperatures above $35^{\circ}C$ and below $20^{\circ}C$; (3) it had optimum nitrite removal ability within a pH range of 6.0-8.0; (4) it removed nitrite more effectively under hypoxic than aerobic conditions. NOBSB1 inoculation did not decrease ammonia or nitrate levels, but eliminated nitrite in a BFT culture tank rearing common carp (Cyprinus carpio). After inoculating the NOBSB1 strain in a BFT culture tank, NOBSB1 controlled and sufficiently reduced the nitrite concentration in the tank.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.52 no.5
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• pp.482-495
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• 2019

This study compared the productivity of fish and vegetables grown using the hybrid biofloc technology-aquaponics (HBFT-AP), a semi-recirculating aquaculture system (SRAS), and hydroponics (HP). For the study of fish productivity (HBFT-AP vs. SRAS), fish were provided feed containing 3.0% monobasic potassium phosphate (MKP) for 18 weeks. After the 18-week feeding trial, the average weight of the sampled population (n=100) was not significantly different (P>0.05), while hematocrit (PCV, %), hemoglobin (Hb, g/dL), and plasma K (mEq/L) were significantly different (P<0.05) between the two groups (HBFT-AP: 47.83%, 15.48 g/dL, and 1.39 mEq/L; SRAS 34.83%, 11.81 g/dL, and 2.48 mEq/L). Leaf vegetable productivity (HBFT-AP vs. HP) was compared in three experiments (EXP 1-3), and slower growth was observed in both groups in EXP 2, in which pH was maintained at 5.0 or less throughout the experiment. During the 18-week feeding trial, total ammonia nitrogen (TAN), $NO_3-N$, and $PO_4-P$ levels increased with time in the HBFT-AP system, while the concentration of $NO_2-N$ remained below 0.1 mg/L throughout the study.

• Journal of fish pathology
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• v.35 no.2
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• pp.185-193
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• 2022

This study investigated carnival behavior in the nursery stage of Fenneropenaeus chinensis. In order to suppress the carnival behavior and improve the survival rate, it was examined whether there was a carnivalism inhibitory effect according to the rearing water of shrimp. In addition, their blood physiological changes were observed. As a result, in the experimental group with the size difference of F. chinensis, the survival rate was the highest in the biofloc technology (BFT) rearing water of olive flounder (75%), and in the experimental group without the size difference, the survival rate was the highest in the seawater experiment group (93%). In both experimental groups, rate of carnival behavior was observed to be low in the fed experimental group regardless of the size difference of F. chinensis. As a result of blood cell analysis of F. chinensis according to the rearing water, the percentage of granulocytes was the highest in the BFT rearing water of flounder (75%) and the lowest in the filtered seawater group (66%). The proportion of semi-granulocytes was the highest at 11% in the shrimp BFT rearing water, and the lowest at 7% in the filtered seawater. The proportion of hyalinocytes was highest in filtered seawater (27%) and lowest in flounder BFT rearing water (16%). These results suggest that carnival behavior and blood composition of F. chinensis may be different depending on the conditions of the rearing water in the nursery stage.

• Journal of Sensor Science and Technology
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• v.30 no.3
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• pp.154-164
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• 2021

In this study, the IoT sensor technology required for improving the survival rate and high-density productivity of individual shrimp in smart shrimp farming (which involves the usage of recirculating aquaculture systems and biofloc technology) was analyzed. The principles and performances of domestic and overseas water quality monitoring IoT sensors were compared. Furthermore, the drawbacks of existing aquaculture monitoring technologies and the countermeasures for future aquaculture monitoring technologies were examined. In particular, for farming white-legged shrimp, an IoT sensor was employed to collect measurement indicators for managing the water quality environment in real-time, and the IoT sensor-based real-time monitoring technology was then analyzed for implementing the optimal farming environment. The results obtained from this study can potentially contribute to the realization of an autonomous farming platform that can improve the survival rate and productivity of shrimp, achieve feed reduction, improve the water quality environment, and save energy.

• Journal of Aquaculture
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• v.22 no.1
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• pp.42-50
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• 2009

Shrimp farming which is entirely conducted in outdoor ponds in the west coast of Korea has been suffered from mass mortality due to viral epizootics. Intensive indoor shrimp culture under limited water exchange can solve these problems of outdoor ponds including viral transmission from environment, pollution due to discharge of rearing water, low productivity and limited culture period. In this study, juvenile L. vannamei (B.W. 0.08-0.09 g) was stocked with $3,000-5,455/m^3$ in density in four raceway tanks (two $12.9\;m^2$, two $18\;m^2$ tanks) and cultured for 42 days with 2.7-3.4% of daily water exchange. Results from four tanks showed FCR of 0.79-1.29, survival of 38.2-48.0%, and yields of $2.49-4.22\;kg/m^3$ which is consistent with 12-20 and 8-14 times higher than those of commercial shrimp hatchery and outdoor pond in Korea, respectively. Concentrations of total ammonia nitrogen in all four tanks were 1.11-1.42 ppm in mean level and did not exceed 6.0 ppm (0.096 ppm of $NH_3$) which is still acceptable levels for shrimp growth. During the culture trial, concentration of $NO_2$-N rapidly increased from stocking, resulting in mean concentration of 18.45-22.07 ppm. It also exceeded 10 ppm over four weeks and maintained at 35-45 ppm for four days in all tanks, accounting for low survival of shrimp due to long-term exposure to high concentration of $NO_2$-N. Nevertheless, the results with survival rate over 38% from raceways which experienced the extreme $NO_2$-N levels suggests that under "biofloc system" white shrimp can acclimate to high $NO_2$-N concentration to some degree.

• Korean Journal of Environmental Biology
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• v.37 no.2
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• pp.129-135
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• 2019

Juvenile Paralichthys olivaceus (mean weight 685.3±36.7 g) were raised in different and closed recirculating bio-floc system (control, bio-ball, and shelter) for 7 months. The water environment such as water temperature, dissolved oxygen, salinity, pH, and alkalinity according to the difference of closed recirculating system remained stable during the rearing period. No significant changes were observed in dissolved inorganic nitrogen such as ammonia, nitrite, and nitrate were observed in different closed recirculation system. The final weights according to the difference of closed recirculating were 1,524 g (control), 1,674 g (bio-ball), and 1,630 g (shelter). The survival rate was higher than 98%, and the final FCRs (Feed coefficient ratio) were 1.2, 1.1, and 1.2. The results of this study indicated high growth and survival rate in all systems.

• Journal of Fisheries and Marine Sciences Education
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• v.27 no.5
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• pp.1229-1235
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• 2015

Juvenile banded catfish(Pseudobagurus fulvidraco, mean length $10.7{\pm}0.42cm$ and mean weight $15.0{\pm}0.23g$) were exposed to varies TAN(total ammonia) concentrations at pH levels of $6.12{\pm}0.51$, $7.00{\pm}0.26$ and $8.04{\pm}0.07$ for 96hrs to check the level of acute toxicity on biofloc technology aquaculture system(BFT). The result showed that cumulative mortalities for juvenile banded catfish at TAN levels 48.95, 55.96, 66.47, and 78.88 mg/L at pH $6.12{\pm}0.51$ were 0, 30, 30, and 50%, respectively. At pH $7.00{\pm}0.26$, its mortalities to TAN 5.20, 11.68, 15.31, and 18.31 mg/L were 0, 10, 20, and 70%, respectively and at pH $8.04{\pm}0.07$, the mortalities to TAN 0.96, 1.49, 2.13, and 3.62 mg/L were 10, 20, 40, and 100%, respectively. Its $96h-LC_{50}$ (median lethal concentration, $LC_{50}$) at pH $6.12{\pm}0.51$, $7.00{\pm}0.26$, and $8.04{\pm}0.07$ were 78.12, 15.87, and 2.21 mg/L for TAN, and 0.05, 0.10, and 0.14 mg/L for $NH_3$, respectively, and the acute toxicity for ammonia to juvenile banded catfish increased exponentially with increase of pH.

• Fisheries and Aquatic Sciences
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• v.24 no.7
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• pp.260-275
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• 2021

Aquaponics is a cultivation system that combines aquaculture and agricultural hydroponics. This study investigated the productivity of leafy vegetables cultivated in the hybrid biofloc technology-aquaponics (HBFT-AP) using Japanese eel fed two kinds of diets (Mash, commercial powdered feed and extruded pellet [EP]) and hydroponics (HP).The mash was fed to the fish in a type of a dough mixed with water for 6 weeks (Exp1) and switched to the EP containing 2.7% monobasic potassium phosphate (MKP) for subsequent 6 weeks (Exp2). Leafy vegetables of 8 cultivar were employed in the experiment and water quality [dissolved oxygen (DO, mg/L), pH, water temperature (℃), electrical conductivity (EC; ㎲/cm), turbidity (NTU), TAN (NH₃ + NH₄⁺) (mg /L), NO₂-N (mg/L), NO₃-N (mg/L) and PO₄-P (mg/L)] was measured 6 times a week. Leafy vegetable productivity (HBFT-AP vs HP) was compared in respective experiment, which was similar or somewhat higher in HBFT-AP. During the 12-week feeding trial, concentrations of nitrite (NO₂-N) and phosphorus (PO₄-P) were kept low in variability while total ammonia nitrogen (TAN) and NO₃-N levels increased with time in HBFT-AP. At the end of two feeding trials, values of weight gain (WG, %), feed efficiency (FE, %), specific growth rate (SGR, %) and protein efficiency ratio (PER) were higher in Exp2 than in Exp1. As well, higher values in hematocrit (PCV, %), plasma K (mEq/L) and inorganic phosphorus (mg/dL) were found (p < 0.05) in Exp2 where fish were fed the EP (EP: 38.60%, 2.80 mEq/L and 7.04 g/dL; Mash: 33.20%, 1.95 mEq/L and 5.50 g/dL). Leafy vegetables in HBFT-AP using Japanese eel fed the EP with MKP 2.7% had a productivity similar (4 kinds of cultivar) or somewhat higher (4 kinds of cultivar) compared to those in HP. Also, Japanese eel fed the EP showed higher values of Pi (m/dL) and K (mEq/L) in plasma compared to those fed commercial powder diet.