• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.1
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• pp.15-24
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• 2017

This study examined the effects of dietary supplementation with citrus by-product (CBP) on the growth, feed utilization, innate immunity, and histology of the gills and intestine of juvenile olive flounder Paralichthys olivaceus during low water temperature season. A vitamin C-free basal diet was regarded as a control and five other diets were formulated that contained 30 and 300 mg of L-ascorbyl-2-polyphosphate (LAPP) or CBP as vitamin C equivalents/kg diet, or the antibiotic oxytetracycline (OTC) (designated as control, LAPP30, LAPP300, CBP30, CBP300, and OTC, respectively). Olive flounder (initial body weight $44.6{\pm}0.32g$) were fed the six experimental diets to apparent satiation for 9 weeks. Growth and feed utilization were significantly higher in CBP30 than in the control and LAPP groups. The lysozyme activity was significantly higher in CBP30 than in LAPP300. Enterocyte height was significantly higher in CBP30 than in the control. The number of goblet cells was increased significantly with LAPP30, LAPP300, and CBP30. These results demonstrate that CBP can reduce or replace vitamin C and antibiotic in the diet of olive flounder during the low-water-temperature season. The optimal CBP supplementation level seems to be approximately 1%, which is equivalent to 30 ppm vitamin C/kg in the fish diet.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.49 no.5
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• pp.683-688
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• 2016

The effects of dietary supplementing natural additives [yacon (YC), ginger (GG), and blueberry (BB)] on growth, feed utilization, and body composition of juvenile rockfish were compared to those of ethoxyquin (EQ), which is commonly used to prevent rancidity of fish feed. A total of 480 fish were distributed randomly into 12 50-L flow-through tanks (40 fish/tank). Four experimental diets were prepared: the control diet (Con) with 0.01% EQ, and the YC, GG and BB diets containing 1% YC, GG, and BB instead of wheat flour. Each diet was assigned randomly to triplicate tanks of fish, which were hand fed to satiation twice daily for 8 weeks. Weight gain of fish fed the YC diet was higher than that of fish fed all other diets. Feed efficiency (FE), protein efficiency ratio (PER), and protein retention (PR) in fish fed the YC diet were higher than those in fish fed the other diets. Whole-body chemical composition of the fish was affected by the additive sources. In conclusion, dietary supplementation with GG effectively improved weight gain and feed utilization (FE, PER, and PR) of juvenile rockfish.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.2
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• pp.157-162
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• 2018

A feeding trial was conducted to investigate the effects of supplementation with four phosphorus (P) additives [mono-calcium phosphate (MCP), dicalcium phosphate (DCP), tricalcium phosphate (TCP) and magnesium hydrogen phosphate (MHP)] on the growth, feed utilization and whole body mineral composition of juvenile olive flounders Paralichthys olivaceus. A basal diet without P supplementation was prepared as a negative control and four supplemental P sources were added at a level of 2%. Triplicate groups of fish (initial mean body weight 11 g) were fed one of the experimental diets to apparent satiation twice a day, at 08:30 and 18:00 for 10 weeks. The final body weights of fish fed the experimental diets ranged from 29.4 g (DCP) to 34.2 g (MCP) and did not differ significantly (P>0.05) among treatments. Similar tendencies were found for all parameters including weight gain (%), specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), feed intake (FI) and survival rate (SR). The hematocrit (%), hemoglobin (g/dL), serum inorganic P and whole body mineral composition did not differ significantly different (P>0.05) among the treatments. Therefore, dietary P addition is not necessary for juvenile olive flounder fed a fish meal-based diet.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.6
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• pp.756-761
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• 2017

This study investigated the growth of juvenile mandarin fish Siniperca scherzeri, reared at high water temperatures. Feed-trained juvenile fish were reared at four water temperatures: 27, 29, 31, and $33^{\circ}C$. The fish were fed to apparent satiation twice daily using pelleted diet. After 10 weeks of feeding trial, the survival exceeded 98% in all groups. The weight gain of fish reared at $31^{\circ}C$ was higher than for fish reared at the other temperatures. The feed efficiency and protein efficiency ratio of fish reared at 29 and $31^{\circ}C$ were higher than for the fish reared at 27 and $33^{\circ}C$. The daily feed intake of fish reared at 27 and $33^{\circ}C$ was higher than for the 29 and $31^{\circ}C$ groups. The whole body moisture content of fish reared at $33^{\circ}C$ was higher than in the $27^{\circ}C$ group. The whole body crude protein and lipid contents of fish reared at $27^{\circ}C$ were higher than in the $33^{\circ}C$ group. The results indicate that suitable rearing water temperature was $31^{\circ}C$ for optimal growth and feed efficiency of juvenile mandarin fish under the experimental conditions.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.53 no.4
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• pp.577-582
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• 2020

This study was conducted to investigate the replacement of fish meal (FM) with a plant and animal protein mixture (wheat gluten, soy protein concentrate, tankage meal and poultry by-product meal) in the diets of juvenile olive flounder Paralichthys olivaceus. The basal diet was formulated to contain 65% FM (Con). Four other experimental diets were formulated with alternative proteins replacing 20%, 30%, 40% and 50% of FM (FM20, FM30, FM40 and FM50, respectively). Taurine and betaine were added to the FM replacement diets. Triplicate groups of fish (mean±SD, 5.41±0.01) were fed the diets to apparent satiation for 15 weeks. After the feeding trial, no significant differences were found between any dietary groups in growth performance, feed utilization, survival, hematological parameters or whole-body composition. This result indicates that a proper mixture of the four protein sources with taurine and betaine supplements can be used as FM replacement to reduce FM levels from 65% to 32.5% in juvenile olive flounder diets.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.6
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• pp.570-578
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• 2012

The present study investigated the effect of diets supplemented with different levels (0, 1, 3, and 5 %) of fig leaf ethanol extract (FLEE) on the nutritional composition of black rockfish Sebastes schlegeli. Fish ($10.05{\pm}0.44g$) were fed to apparent satiation twice daily for 8 weeks. Adding FLEE decreased crude lipid levels and increased crude protein and ash. Among the three organic acids in the whole body of black rockfish, lactic acid was predominant, followed by citric acid and oxalic acid. Five free sugars were found in all groups. Fucose and glucose were the dominant free sugars in the FLEE-added group. The abundant fatty acids in the FLEE-added group were C16:0, C18:1-cis (n9), and C22:6n-3. The major amino acids in the samples were glutamic acid, aspartic acid, glycine, leucine, alanine, lysine, and arginine. The abundant free amino acids in the FLEE-added group were taurine, glutamic acid, alanine, leucine, and arginine.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.45 no.6
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• pp.648-653
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• 2012

The present study examined the effects of dietary supplementation with nucleotide (inosine monophosphate product, IMP) on the growth performance, feed utilization, and non-specific immune responses of juvenile tilapia Oreochromis niloticus. Triplicate groups of tilapia (initial body weight, $7.4{\pm}0.04$ g) were fed experimental diets containing 0%, 0.05%, 0.1%, and 0.2% IMP. Fish were fed six times a day until apparent satiation for 13 weeks. At the end of the feeding trial, final body weight and food utilization of fish fed 0.1% IMP were significantly higher than those of fish fed the control diet. Results of hematological parameters were not affected by dietary IMP. However, blood protein level was significantly higher in the 0.05% treatment, as compared to that of the control and 0.2% IMP diets. Myeloperoxidase activity was higher in fish fed 0.1% IMP than in fish fed the control and 0.2% IMP diets. These results suggest that dietary supplementation with IMP can enhance the growth performance, feed utilization, and innate immune response of juvenile tilapia. The optimal IMP supplementation level appears to be 0.1% in practical feed formulations for tilapia.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.43 no.6
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• pp.573-580
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• 2010

The study investigated the effect of diets supplemented with different levels (0 and 2.5%) of yuza (Citrus junos Sieb ex Tanaka) on the nutritional characteristics of eels (Auguilla japonica). Fish ($9.8{\pm}1.3g$) was fed to apparent satiation twice daily for 8 months. There were no significant differences in proximate composition among the treatment groups, except for the ash and carbohydrate contents (P<0.05). The vitamin C content of eel muscle in the yuza-added group was two-times higher than in non-added groups (P<0.05). Among eight organic acids in eel muscle, lactic acid was predominant, followed by citric acid, oxalic acid, malic acid, and acetic acid. Eels fed a 2.5% yuza diet had the highest lactic acid content in all groups. Six sugars were found in all groups and glucose was the major sugar. Glucose and maltose were the dominant sugars in the yuza-added group. The abundant fatty acids in the yuza-added group were C18:1 n-9, C16:0, and C16:1 n-7, which comprised over 80% of the total fatty acids. The major amino acids in samples were glutamic acid, aspartic acid, lysine, and leucine. There were few differences in the free amino acid compositions among the groups. However, histidine was the predominant amino acid and constituted over 53% of the total free amino acids.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.50 no.4
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• pp.372-377
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• 2017

A feeding trial was conducted to evaluate the effects of partial replacement of fishmeal (FM) protein in a practical diet for rockfish Sebastes schlegeli juveniles with mealworm Tenebrio molitor meal (WM), in terms of growth performance, feed utilization, whole body composition and hematological parameters. Four isonitrogenous and isoenergetic diets were formulated to contain 8, 16, 24 and 32% WM (designated as WM8, WM16, WM24 and WM32). A FM-based diet without WM inclusion was used as a control. Triplicate groups of rockfish ($2.6{\pm}0.07g$) were hand fed one of the experimental diets to visual satiation twice a day for 8 weeks. Weight gain of fish fed the WM32 diet was lower than that of control. No significant differences were found in daily feed intake, feed efficiency and protein efficiency ratio. The whole-body protein content of fish fed WM0 and WM8 diets were significantly higher than that of fish fed WM32 diet. No statistical differences were observed in hematological parameters. These results indicate that WM has potential as alternative to FM in practical diets for juvenile rockfish and can be used at an inclusion level of up to 24% without having a significant negative effects on growth and feed efficiency.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.47 no.6
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• pp.790-795
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• 2014

A feeding trial was conducted to investigate the effects of dietary carotenoids sources on growth and skin color of red- and white-colored fancy carp Cyprinus carpio var. koi. Nine experimental diets (designated as Con, CP, PA, SP, OP, MB, TO, BE and PO) were formulated to contain Carophyll Pink, red paprika, Spirulina, Opuntia, mandarin bark, tomato, beet and Porphyra, respectively. Each experimental diet was fed to two replicate groups of fish (22.9 g/fish) to visual satiation three times a day for 8 weeks. Weight gain and feed efficiency of fish fed the diets containing Spirulina or Opuntia were higher than those of fish fed the control diet (P<0.05). The values of $a^*$, $L^*$ and $b^*$ of fish skin were significantly changed by dietary carotenoids sources (P<0.05). The $a^*$ values of fish fed the diets containing Carophyll Pink, red paprika and Spirulina were higher than those of fish fed other diets (P<0.05). The skin total carotenoids of fish fed the diets containing Spirulina and Opuntia were higher than those of others (P>0.05). Based on the results of this study, it can be concluded that dietary inclusion of red paprika and Spirulina pacifica could increase the skin redness of red- and white-colored fancy carp.