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The effect of cobalt-chloride on the production parameters and homogenity of barramundi (Lates calcarifer) larvae
21-25Views:395Barramundi (Lates calcarifer) is a predatory fish species native in Southeast Asia and Australia. Based on the geothermal potentiality of Hungary the high market potential warm-water fish barramundi can be produced economically. Living nourishment organisms such as Artemia nauplii play an essential role in the larval rearing of barrramundi. However, zooplanktons in natural aquatic enviroments contain minerals in a higher concentration than the usually fed newly hatched Artemia. Therefore the goal of recent study was to investigate the effect of cobaltchloride on the larval growth and survival of barramundi when fed individually and combined with Zn and Mn supplemented Artemia.
In our experiment a 24 hours period was used for the enrichment of newly hatched Artemia nauplii with cobalt chloride in itself, as well as in combination with zinc sulphate and manganese chloride. A total of 1900 barramundi larvae from 15–30 day post hatching were fed with supplemented Artemia in 9 groups of treatments in duplicate. The growth performance and elemental concentration of 40 larvae from each group was determined. All the groups produced significantly improved growth compared to the control (p<0.05). The lower concentration of individual Co supplementation resulted in a higher growth performance while the opposite dose relation occured when combined the Co with Mn. Cobalt had a significant negative effect on the Mn uptake of the larvae – significantly higher Mn accumulation compared to the control group was only observed when Mn was fed in itself (p<0.05). In case of Co-Zn-1 and Co-Zn-2 treatments significantly higher Zn concentration was measured than in the others (p<0.05).
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Utilization of live feeds in fish larviculture: A review
103-116Views:18This review examines the significance of live feeds in commercial aquaculture industry for production of fish and shrimp larvae, along with various challenges and prospects. Live feeds are an essential food source in larviculture, especially for marine fish, which depend on them for nutrition during the initial days of exogenous feeding. They are palatable, highly digestible, and their movement stimulates natural hunting and foraging instincts, promoting better development, lowering captivity stress, and increasing survival rates. Artemia is the most commonly used live feed in larviculture; however, it has low levels of omega-3 HUFA. Copepods are the most nutritionally rich live feed, containing high levels of DHA and EPA. Despite these benefits, they are less frequently used in larviculture due to technical challenges associated with large-scale cultivation at high densities. The use of live feed is labour-intensive and costly. The feeding period for fish larvae can be shortened using a co-feeding strategy. Microalgae rich in DHA have been utilized to enrich live feeds. Further research is needed to determine the most effective approach to significantly reduce the weaning time of fish larvae from live feed. This will lead to gradual and eventual complete replacement of life feed in the near future.
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The use of essential trace elements in the juvenile rearing of barramundi (Lates calcarifer
33-38Views:367Barramundi (Lates calcarifer L.) is a predatory fish species native in Southeast Asia and Australia. Based on the geothermal potentiality of Hungary the warm-water fish can be reared successfully. Zooplankton in the wild contains minerals in a higher concentration than the usually fed newly hatched Artemia nauplii, therefore essential trace elements, such as cobalt, zinc and manganese play an important role in the larviculture of barramundi. Cobalt is vital in trace amount for many living functions of vertebrates, however, lower number of papers are available considering the nutritional aspects. Nevertheless. improved growth performance was observed in cases of some fish species when diet was supplemented with CoCl2. Zinc and manganese are also vital for optimal growth and accordingly are investigated and applied diet supplements in aquaculture.
The main aim of the recent study is to investigate the effects of cobalt, manganese and zinc on the growth performance and homogeneity of fish when a commercially available dry diet is supplemented with trace elements individually and in combined treatments. A total of 6 treatments were set in a randomized blocked design where the concentrations of the applied elements were 50 mg kg-1 for CoCl2, for ZnSO4 and for MnCl2 individually, as well as for CoCl2 along with ZnSO4 and for CoCl2 along with MnCl2 in combination. Although the production parameters of larval barramundi were positively affected by the addition of trace elements when the retention of minerals occurred through nourishment living organisms, statistically no differences were found between the treatments considering the growth performance of barramundi juveniles either when dry feed was supplemented with cobalt, manganese or zinc (p>0.05). While the use of cobalt and manganese in combined treatments produced a less uniform larvae in size and as a consequence of increased heterogeneity, survival was significantly reduced by the cannibalism, the sizes distribution of barramundi juveniles wasn’t affected by the dry diet supplementation of these elements.