• Journal of Aquaculture
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• v.2 no.2
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• pp.53-90
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• 1989

Feeding proper level of ration matchable with the appetite of fish will enhance production and also prevent waste of food and its consequence, side effects such as pollution of culture medium. To pursue this goal, elaborate studies on dissolved oxygen concentrations- as the major force in inducing appetite and the growth outcome are necessary. The growth of common carp of 67, 200, 400, 600, and 800 gram size groups was studied at oxygen concentrations ranging from 2.0 to 6 mg/$\iota$ in relation to rations from 1 to as many percent of the initial body weight as could be consumed under constant temperature of $25^{\circ}C$. The results from the experiments are summarized as followings; 1. Appetite: The smaller fish exhibited higher degree of appetite than the bigger ones at the same oxygen concentrations. The bigger the fish the less tolerant it was to the lower oxygen thersholds, and the degree of tolerence decreased as ration level increased. 2. Growth : Growth rate (percent per day) increased - unless consumption was suppressed by low oxygen levels- as the ration was increased to maximum. In case of 67 g fish, it reached the highest point of $5.05\%$ / day at $7\%$ ration under 5.0 mg/$\iota$ of oxygen. In case of 200 g fish, the maximum growth rate of $3.75\%$/day appeared at the maximum ration of $6\%$ under 5.5 mg/$\iota$ of oxygen. In 400 g fish, the highest growth of $3.37\%$/day occurred at the maximum ration of $5\%$ and 6.0 mg/$\iota$ of oxygen. In 600 g fish, the highest growth rate of $2.82\%$ /day was at the maximum ration of $4\%$ under 5.5 mg/$\iota$ oxygen. In case of 800g fish, the highest growth rate of $1.95\%$/day was at maximum tested ration of $3\%$ under 5.0 mg/$\iota$ oxygen. 3. Food Conversion Efficiency: Food conversion efficiency ($\%$ dry feed converted into the fish tissue) first increased as the ration was increased, reached maximum at certain food level, then started decreasing with further increase in the ration. The maximum conversion efficiency stood at higher feeding rate for the smaller fish than the larger ones. In case of 67 g fish, the maximum food conversion efficiency was at $4\%$ ration within 3.0-4.0 mg/$\iota$ oxygen. In 200g fish, the maximum efficiency was at $3\%$ ration within 4.0-4.5 mg/$\iota$ oxygen. In 400g fish, the maximum efficiency was at $2\%$ ration within 4.0 - 4.5 mg/$\iota$ oxygen. In 600 and 800g fish, the maximum conversion efficiency shifted to the lowest ration ($1\%$) and lower oxygen ranges. 4. Behaviour: The fish within uncomfortably low oxygen levels exhibited suppressed appetite and movements and were observed to pass feces quicker and in larger quantity than the ones in normal condition; in untolerably low oxygen the fish were lethargic, vomited, and had their normal skin color changed into pale yellow or grey patches. All these processes contributed to reducing food conversion efficiency. On the other hand, the fish within relatively higher oxygen concentrations exhibited higher degree of movement and their food conversion tended to be depressed when compared with sister groups under corresponding size and ration within relatively low oxyen level. 5. Suitability of Oxygen Ranges to Rations: The oxygen level of 2.0- 2.5 mg/$\iota$ was adequate to sustain appetite at $1\%$ ration in all size groups. As the ration was increased higher oxygen was required to sustain the fish appetite and metabolic activity, particularly in larger fish. In 67g fish, the $2\%$ ration was well supported by 2.0-2.5 mg/$\iota$ range; as the ration increased to $5\%$, higher range of 3.0-4.0 mg/$\iota$ brought better appetite and growth; from 5 till $7\%$ (the last tested ration for 67 g fish) oxygen levels over 4.0 mg/$\iota$ could sustain appetite. In 200 g fish, the 2 and $3\%$ rations brought the best growth and conversion rates at 3.5-4.5 mg/$\iota$ oxygen level; from 3 till $6\%$ (the last tested ration at 200 g fish) oxyge groups over 4.5 mg/$\iota$ were matchable with animal's appetite. In 400, 600, and 800 g fish, all the rations above $2\%$ had to be generally supported with oxygen levels above 4.5 mg/$\iota$.

• Journal of Internet Computing and Services
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• v.25 no.2
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• pp.49-55
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• 2024

This paper proposes PredFeed Net, a neural network model that mimics the food distribution of fish farming experts. Unlike existing food distribution automation systems, PredFeed Net predicts food distribution by learning the food distribution patterns of experts. This has the advantage of being able to learn using only existing environmental data and food distribution records from food distribution experts, without the need to experiment by changing food distribution variables according to the environment in an actual aquarium. After completing training, PredFeed Net predicts the next food ration based on the current environment or fish condition. Prediction of feed ration is a necessary element for automating feed ration, and feed ration automation contributes to the development of modern fish farming such as smart aquaculture and aquaponics systems.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5206-5210
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• 2012

We studied the effect of food concentration on grazing, growth and fecundity of cyclopoid copepod Paracyclopina nana. Marine phytoplankton Tetraselmis suecica was used as a livefood for the copepod. Six stage compositions were used and food concentrations for the experiment were 0.5, 1, 2, 5, 10, 20, 40, 60 and $80{\times}10^4$ cells/mL. Range of food concentrations with 0.2, 0.5, 1, 2, 3 and $4{\times}10^4$ cells/mL were used for nauplii production experiment. Grazing rates of P. nana in all developmental stages on the different concentrations were increased with increasing diet concentration. While the growth of nauplius was not affected by increase of food concentration, food concentration outside of $1{\times}10^4$ to $5{\times}10^4$ cells/mL range negatively affected that of copepodite. Daily nauplii production was increased with increasing food concentration but $3{\times}10^4$ and $4{\times}10^4$ cells/mL treatments were not significantly different with $2{\times}10^4$ cells/mL treatment. As a result, optimum concentration of T. suecica for mass culture of P. nana was considered to be 5,000 cells/mL for nauplius stage, 10,000 cells/mL for copepodite stage and adult male, 20,000 cells/mL for adult female, respectively.

• Journal of Navigation and Port Research
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• v.34 no.10
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• pp.793-797
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• 2010

The depleting fishes resource and water pollution in coast has a decisive effect on the fish farm and fisheries. For solving these problems the fish farms are moving to the offshore. The fish farms in offshore have to design the strong mechanism as compared with cost's fish farm, and operate by the remote feeding system and monitoring system for safety and management.. This paper describes a remote feeding system for fish farms in offshore. The amount of feed is depending on temperature and fish weight. The fish farm temperature is changed extremely in offshore than on land side. This paper described that the feed amount is calculated automatically according to temperature and fish weight, and the remote feed system. The performance of remote feed system is tested with model.

• Journal of Aquaculture
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• v.21 no.3
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• pp.184-189
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• 2008

Tryptic enzyme activities in the digestive glands (hepatopancreas) and digestive tracts of Pacific white shrimps Litopenaeus vannamei were assayed at three water temperature regimes. At $26^{\circ}C$, trypsin activity in the hepatopancreas was 200% higher than at $23^{\circ}C$ and 300% higher than at $20^{\circ}C$. The highest foregut trypsin activity levels showed no significant difference in the temperature regimes, but the time between peaks in foreguts and midguts shortened at higher temperature. In the midgut, the level of enzyme activity was highest at $26^{\circ}C$ regardless of the amount of ingested feed. The ratio of foregut and/or midgut dry weight to the body wet weight indicated feed movement through the digestive track directly and gave accurate account about the feeding mechanism. Maximum feed ingestion in the foregut was equivalent to 0.6% of the body weight (wet weight) at $23^{\circ}C$, 0.4% of the body weight at $20^{\circ}C$, and 0.5% of the body weight at $26^{\circ}C$. In view of the temperatures chosen for this study, although maximum ingestion was observed at $23^{\circ}C$, the shrimps showed highest enzyme activity, but lowest feed retention time at $26^{\circ}C$ and lowest enzyme activity, but highest retention time at $20^{\circ}C$.

• Korean Journal of Environment and Ecology
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• v.21 no.1
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• pp.30-37
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• 2007

Pellets and prey remains were analyzed to compare diets and foraging tactics of Eurasian eagle owls (Bubo bubo) in two different habitat types: forested areas and open fields. Overall 150 prey items of three taxa were identified from 66 pellets and 82 prey remains, and the birds were the most important prey in biomass (78.04%) and in frequency (56.67%). Eurasian eagle owls frequently used rats (Rattus spp.), ring-necked pheasants (Phasianus colchicus), and stripped field mice (Apodemus agrarius), but the ring-necked pheasant was most important in biomass in both habitat types. The owls generally foraged various prey in biomass but the mean mass of vertebrate prey used by the Eurasian eagle owls was 503.3g in central Korea. According to the comparison of diets in the two different habitat types, the owls used bigger and more diverse prey in forested areas than in open fields. In forested areas, the Eurasian eagle owls frequently foraged the pheasants and Mandarin ducks (Aix galericulata), but they preferred prey of particular sizes to prey of particular taxa. In open fields, however, the owls showed opportunistic foraging tactics by selecting many small mammals such as rodents or a few large birds.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.10 no.4
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• pp.275-279
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• 1977

During the experimental rearing period of common carp in a small simple recirculating aquarium combined with frequent exchanges of water and cleanings, some observations were made on the conditions of fish growing which was directly and instantly affected by the cleaning frequency of strainer, changing rate of water, division and frequency of feed supply, prohibition of excess feeding and the amount of dissolved oxygen. The fish don't seem to be stressed by the manipulation for the change of rearing water, cleaning of detritus in the strainer and filter. It appeared that the most hazzardous matters to fish growth were : 1) supplying feed when fish do not show active response to feed supplied, and 2) giving ample amount of feed at one time. When especially the amount of the feed is within the range fish instantly can swallow, the water clarity is maintained even after feeding operation, but if any excess amount is given the fish intake into mouth much more feed than able to instantly swallow and try to swallow it resulting in much dissolving and suspension of feed materials in water, making the water quite cloudy. Consequently all the water as well as filter bed becomes significantly polluted.

• Korean Journal of Environmental Biology
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• v.40 no.4
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• pp.604-614
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• 2022

This study analyzed habitat status of barn swallows within 800 m and changes in potential food resource occurrence for 63 nests (Seocheon 23, Sejong 40) where barn swallows breeding was confirmed in Seocheon and Sejong in 2019 and 2020. As a result of checking habitat compositions of barn swallows in the study area, Sejong showed more varieties of habitat types than Seocheon, showing a larger number of dominant groups. Such large number of dominant groups was found to be an advantageous habitat factor for producing flying insects as potential food resources for barn swallows. As for the production of potential food resources, Seocheon had the highest production in dwelling and stream and Sejong had the highest production in the stream. The production of potential food resources differed in production season by habitat type. This study analyzed compositions of the habitat around the breeding site of swallows. It provides basic data necessary for protecting barn swallow habitats by comparing the production timing and production volume of potential food resources occurring in the habitat.

• Journal of Marine Life Science
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• v.1 no.2
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• pp.121-125
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• 2016

This study examined the feeding response of the harpacticoid copepod, Tigriopus japonicus exposed to WAF or CEWAF to understand whether decreased feeding of the copepod by oil exposure is induced by food avoidance or medium toxicity. In the medium without WAF, there was no difference in the ingestion rate of the copepod among all polluted diets those were exposed to different concentrations of WAF. The present of WAF in the medium however caused a decrease in the ingestion rate at 100% WAF treatment. In the mixed diet treatment with adhesive diatoms and Tetraselmis suecica, T. japonicus had significantly lower ingestion rate on adhesive diatoms than on others in the medium with CEWAF. As a result, decreased ingestion of T. japonicus by oil exposure was caused by oil toxicity in medium, which may not have directly related with an avoidance of polluted food organisms.

• Journal of the Korea Organic Resources Recycling Association
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• v.14 no.4
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• pp.104-112
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• 2006

Population growths of earthworm were investigated when the earthworm populations with different levels of initial densities per unit area were fed with cow dung mixed with paper mill sludge. The tested levels of earthworm densities were as follows; $1kg/m^2$, $2kg/m^2$, $3kg/m^2$, $5kg/m^2$. There were no significant differences in population growth rates 60 and 90 days after feed supply among the tested densities of earthworm. Therefore, it was suggested that initial densities of earthworm populations per unit area higher than $3kg/m^2$ should not be favorable because of the cost for purchasing earthworm. Vermicomposting rates of earthworm on feed were also investigated when different amounts of feed were supplied repeatedly to unit area of nursery bed with $5kg/m^2$ of initial densities earthworm populations. The tested amounts of feed at each supplying time were as follows; $16kg/m^2$, $24kg/m^2$, $32kg/m^2$, $40kg/m^2$. The more the amount of feed at each supplying time, the higher vermicomposting rate and population growth rate. Therefore, it should be more favorable for earthworm breeders to supply more than $40kg/m^2$ of feed at each supplying time, because it would reduce time and labor cost.