• Asian-Australasian Journal of Animal Sciences
• /
• v.27 no.8
• /
• pp.1141-1149
• /
• 2014

The present study was conducted to investigate a supplemental effect of magnesium hydrogen phosphate (MHP, $MgHPO_4$) as an alternative phosphorus (P) source on growth and feed utilization of juvenile far eastern catfish (Silurus asotus) in comparison with three conventional P additives (monocalcium phosphate (MCP), dicalcium phosphate (DCP) and tricalcium phosphate [TCP]) as positive controls. A basal diet as a negative control was prepared without P supplementation and four supplemental P sources were added at the level of 2%. Five groups of 450 fish having mean body weight of 11.3 g following 24 h fasting after three week adaptation period were randomly distributed into each of 15 tanks (30 fish/tank). Fish were hand-fed to apparent satiety twice a day for 8 weeks. Fish fed MHP had weight gain (WG), protein efficiency ratio and specific growth rate comparable to those fed MCP. Fish fed MHP and MCP had feed efficiency (FE) significantly higher (p<0.05) than those fed DCP. Fish groups fed control and TCP showed the lower FE than the other groups which was significantly different (p<0.05) from those of fish fed the other diets. Survival rate was not significantly different (p>0.05) among treatments. Fish fed control had the lowest hematocrit, which was significantly different (p<0.05) from that of fish fed MHP. Fish fed MCP and MHP had plasma P higher (p<0.05) than fish fed the other diets. Relative efficiencies of MCP, DCP and TCP to MHP were found to be 100.5 and 101.3%, 92.0 and 91.6%, and 79.1 and 80.9% for WG and FE, respectively. P availability was determined to be 88.1%, 75.2%, 8.7%, and 90.9% for MCP, DCP, TCP, and MHP, respectively. Consequently, MHP recovered from wastewater stream showed that as an alternative P source its performance was comparative with MCP on growth and feed utilization of juvenile far eastern catfish.

• Development and Reproduction
• /
• v.21 no.2
• /
• pp.193-204
• /
• 2017

The influence of triploidization on histological characteristics of retina, trunk kidney, liver and midgut tissue, and cell cycle of tail fin and gill tissue in far eastern catfish, Silurus asotus were analyzed. In the infertile triploid fish, the nucleus and/or cell size of secondary proximal tubule cells of trunk kidney, hepatocyte and midgut epithelium are much larger than those of the corresponding cells in the diploid fish (P<0.05). However, triploid tissue showed fewer number of outer nuclear layer in retina and nuclei in secondary proximal tubule of trunk kidney than those for diploid tissue. The mean percentages of the $G_l-$, the S- and the $G_2+M-phase$ fractions were 92.5%, 3.2% and 4.3% in tail fin tissue of diploid, and 93.4%, 2.6% and 4.0% in those of triploid, respectively. There were no significant differences in the percentages of each cell cycle fraction between diploid and triploid. The mean percentages of each phase fractions were 75.1%, 11.1% and 13.8% in gill tissue of diploid and 85.2%, 8.9% and 5.9% in those of triploid, respectively. The differences of cell cycle between tail fin tissue and gill tissue were statistically significant in diploid and triploid (P<0.05). Also, the differences between diploid and triploid were statistically significant in tail fin tissue and gill tissue (P<0.05). Cyclin D1 and cyclin E expressions were not significantly difference between gill tissue and tail fin tissue, and protein expressions of induced triploid were higher than those of diploid. Results from this study suggest that some characteristics in the triploid exhibiting larger cell and nucleus size with fewer number of cell than diploid can be used as an indicator in the identification of triploidization and ploidy level in far eastern catfish.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.1
• /
• pp.56-61
• /
• 1999

Oxygen consumption rate of Far eastern catfish, Silurus asotus, weighing 280g, was measured using continuous flow respirometry chamber linked computer monitoring system. Mean oxygen consumption rates at $15^{\circ}C,\;20^{\circ}C,\;25^{\circ}C$, and $30^{\circ}C$ were ranged in 35.2$\~96.4mg\;O_2/kg$ fish/hr, 78.6$\~127.9mg\;O_2/kg$ fish/hr, 120.1$\~231.7mg\;O_2/kg$ fish/hr, and 197.5$\~352.3mg\;O_2/kg$ fish/hr, respectively. The oxygen consumption rates increased with increasing water temperature (p<0.05). A photoperiod-mediated oxygen consumption rates was higher during the light period than during the darkness (P<0.05). When acclimated with different photoperiods, 24L:0D, 12L:12D, and 0L:24D, the lowest oxygen consumption rate was observed in the continuous darkness (0L:24D). The differences between maximum and minimum oxygen consumption rates oyer 24 hour increased with increasing water temperature and the difference was the highest in 12L:12D. Oxygen consumption rate changed suddenly at dawn and at dusk.

• Korean Journal of Ichthyology
• /
• v.21 no.2
• /
• pp.100-105
• /
• 2009

Histological study of normal and albinic catfish Silurus asotus produced in aquaculture has been carried out on organs such as the eye, the barbel, the dorsal fin, and the skin (including dorsal, ventral and lateral regions). Although individuals have no differences in morphological appearance, their colors showed clear difference as follows: the normal catfishes were black overall, but the albinic ones have a yellowish-white color over the whole body, red eyes and white barbels. All the organs investigated were fundamentally very similar in structure. Regarding the distribution and density of the melanin pigments, however, the albinic catfish have no melanin in the skin and eye, particularly in the basement membrane of the epidermis and the pigment epithelial layer in the retina, while the normal catfish have lots of melanin. This phenomenon may coincide with the so-called $i^1/i^1$ type of oculocutaneous albinism.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.52 no.2
• /
• pp.159-172
• /
• 2019

This study investigated the effects of dietary monobasic potassium phosphate (MKP) on the growth of the far eastern catfish Silurus asotus and four leafy vegetables in a hybrid biofloc technology aquaponic system. To an experimental diet containing 45% protein and 7% lipid, 1, 2, 3 or 4% MKP was added and was designated as MKP1, MKP2, MKP3, and MKP4, respectively. The optimum MKP levels were determined for the growth of fish and four leafy vegetables over 10 weeks. After the 10-week feeding trial, weight gain, feed efficiency, specific growth rate and protein efficiency ratio were higher in the fish groups fed MKP2 and MKP3 than in the other groups (P<0.05). The growth of the four leafy vegetables was also higher in the fish groups fed MKP2 and MKP3. Water quality [dissolved oxygen, pH, water temperature, electrical conductivity, turbidity, total ammonia nitrogen (TAN), $NO_2-N$, $NO_3-N$ and $PO_4-P$] was measured six times a week using a portable water quality meter and reagent measurements. The TAN (4.58-20.40 mg/L), $NO_3-N$ (24.12-52.40 mg/L) and $PO_4-P$ (20.38-48.48 mg/L) levels increased with time, while the $NO_2-N$ level remained below 0.1 mg/L throughout the study.

• Asian-Australasian Journal of Animal Sciences
• /
• v.28 no.1
• /
• pp.111-119
• /
• 2015

A growth trial was conducted to determine the optimal incorporation level of dietary magnesium hydrogen phosphate (MHP, $MgHPO_4$), which was manufactured from swine manure and phosphorus (P), required by juvenile far eastern catfish (Silurus asotus). Graded MHP of 0.5%, 1.0%, 1.5%, and 2.0%, and 2.0% monocalcium phosphate (MCP) each was added to the basal diet (control) in lieu of cellulose to become the range of available P (AP) from 0.4% to 0.8% of which diets were designated as control, MHP0.5, MHP1.0, MHP1.5, MHP2.0, and MCP, respectively. Control diet contained fish meal (20%), soybean meal (40%), wheat flour (27%), corn gluten meal (5%), fish oil (2%) and soy oil (2%) as main ingredients. Following a 24 h fasting, 540 fish with a mean body weight of 11.8 g were randomly allotted to 6 groups in triplicate, whereby 18 tanks ($0.4{\times}0.6{\times}0.36cm$, water volume of 66 L) were prepared. The feeding experiment lasted for 8 weeks. Fish group fed the control diet showed the lowest weight gain (WG) and feed efficiency (FE) among treatments. The WG was, however, not significantly different (p>0.05) from that of fish group fed MHP0.5. Fish group fed MHP2.0 showed the highest WG and FE of which values were not significantly different from those of fish groups fed diets MHP1.0 and MHP1.5 as well as MCP (p>0.05) except fish groups fed control and MHP0.5. Aspartate aminotransferase was significantly decreased with an increase in available P, while alanine aminotransferase did not show a significant difference among treatment. The highest inorganic P in plasma was observed in fish fed MHP2.0. From the present results, a second-order regression analysis revealed that the optimal dietary MHP level and the AP requirement were found to be 1.62% and 0.7%, respectively.

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