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  • 1
    Electronic Resource
    Electronic Resource
    Effect of Time of Feeding on Growth of Channel Catfish (1995)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 26 (1995), S. 0 
    Details
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Channel catfish fingerlings were stocked into 16 0.04-ha ponds at a rate of 24,700 fish/ha on 5 May 1992. Four replicate ponds were used for each of the following treatments: 1) fed once daily at 0830h; 2) fed once daily at 1600h; 3) fed once daily at 2000h; and 4) fed on demand using demand feeders. Fish on the first three treatments were fed to satiation. All fish were harvested 145d after stocking. Results from this study showed that when channel catfish raised in ponds were fed once daily to satiation, time of feeding had no significant impact on water quality, feed consumption, feed conversion, weight gain, or body proximate composition. Fish fed on demand consumed more feed than fish fed once daily to satiation, but difference in weight gain was not significant. These data indicated that feeding time may not be critical for channel catfish production as long as fish are fed when dissolved oxygen is sufficient. Although feeding at night was not detrimental in this study, night feeding is not recommended on large ponds unless sufficient aeration is available to quickly provide oxygen in an emergency—and even then it would be problematic.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-7345.1995.tb00261.x
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  • 2
    Electronic Resource
    Electronic Resource
    Evaluation of Limnocorrals for Studying the Effects of Phytotoxic Compounds on Plankton and Water Chemistry in Aquaculture Ponds (2000)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 31 (2000), S. 0 
    Details
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract.— Two studies were conducted to evaluate the potential use of limnocorrals (in situ enclosures) for evaluating the effects of phytotoxic compounds on phytoplankton community structure and water quality. Limnocorrals consisted of open-bottomed, fiberglass cylinders that were 2.44 m in diameter and 1.53 m high. The enclosures were placed in an aquaculture pond and allowed to settle 10–20 cm into the bottom mud, forming a watertight seal that isolated approximately 5.5 m3 of pond water. The first study evaluated the effect of water mixing on environmental conditions within limnocorrals. Mixing was accomplished by injecting air through airstones suspended inside the enclosures. Conditions in unmixed limnocorrals rapidly deviated from conditions in the pond and in aerated enclosures, with overall phytoplankton biomass decreasing while abundance of cyanobacteria and concentrations of soluble reactive phosphorus increased. Conditions in limnocorrals with continuous mixing also deviated from conditions in the pond. Environmental conditions among replicate mixed enclosures were, however, relatively consistent and stable for at least 2 wk. The second study evaluated the use of limnocorrals for testing the effects of phytotoxic compounds on phytoplankton community structure and water quality. A commercial chelated copper algicide was added to randomly selected, mixed limnocorrals at the label-recommended rate. The algicide killed nearly all phytoplankton in the treated enclosures within 1 wk; however, treated limnocorrals were rapidly recolonized by green algae and diatoms. Conditions in untreated limnocorrals remained relatively stable and consistent among replicates for 16 d, after which total phytoplankton biomass began to decrease, possibly due to nutrient depletion within the enclosures. Although conditions inside the enclosures deviated with time from those in the surrounding pond water, mixed limnocorrals appear to provide a convenient and reliable method for short-term studies of algicides and other water quality manipulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-7345.2000.tb00890.x
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  • 3
    Electronic Resource
    Electronic Resource
    Tissue Residues of Diuron in Channel Catfish Ictalurus punctatus Exposed to the Algicide in Consecutive Years (2003)
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the World Aquaculture Society 34 (2003), S. 0 
    Details
    ISSN: 1749-7345
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: In 1999, the United States Environmental Protection Agency granted an emergency exemption under Section 18 of the Federal Insecticide, Fungicide. and Rodenticide Act authorizing the use of the algicide diuron [3-(3,4-dichlorophenyl)-1,1-dimethylurea] to manage cyanobacterial off-flavors in channel catfish Ictalurus punctcatus. Catfish may remain in ponds for more than one growing season and may therefore be exposed to more than one set of diuron treatments. This study was conducted to determine whether diuron residues in fish carry over from one year to the next and, if so, whether the cumulative exposure causes residues to exceed the tolerance level of 2.0 mg/kg in fillets. Catfish in earthen ponds were exposed to the label-specified treatment protocol of nine consecutive weekly applications of diuron at 0.01 mg/L in the fall of one year and again the following spring. Diuron concentrations in fillets were below limits of detection (0.05 mg/kg) in all fish (N = 18) prior to the initial diuron treatment series. Immediately after the ninth weekly diuron application in the fall. tissue diuron levels averaged 0.353 mg/kg (pooled SEM = 0.036; range = 0.078–0.724 mg/kg; N= 18). On the day before the second set of diuron treatments 6 mo later. diuron concentrations were below limits of detection in all fish sampled. Immediately after the second set of nine weekly diuron applications, tissue concentrations averaged 0.127 mg/kg (pooled SEM = 0.015; range = not detected to 0.191 mg/kg; N = 18). This study showed that diuron residues in channel catfish were depleted within 2 to 4 mo after exposure to the chemical and there was no carryover of residues in fish from one year to the next. Maximum residue levels in catfish fillets were less than half the tolerance level of 2.0 mg/ kg.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1749-7345.2003.tb00057.x
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