Demand feeding system using an infrared light sensor for brown-marbled grouper juveniles, Epinephelus fuscoguttatus

In general, demand feeding devices are equipped with a mechanical trigger switch. Such a switch is not suitable for juvenile fish with a small body size, because the body weight is insufficient to trigger the feeder. An infrared light sensor that does not require the fish to push a feeder switch is more suitable for small fish. The brown-marbled grouper Epinephelus fuscoguttatus is an important fish species in Southeast Asia. The purpose of this study was to compare the growth rates (GRs) of brown-marbled grouper juveniles reared using customised demand feeding devices with an infrared light sensor (the infrared light demand feeder (IRDF) group) and automatic feeding devices (the automatic feeder (AF) group). The results indicated that GRs of standard lengths and body weights showed no significant differences using one-way analysis of variance; however, the standard length of the IRDF group showed a tendency of a higher GR than the AF group. Although the feed conversion ratio (FCR) also showed no significant difference, the FCR of the IRDF group was more efficient, indicating that the IRDF group yielded a more desirable FCR. These results indicate that IRDF can be used in the culture of brown-marbled grouper juveniles. In view of the working schedule of the fish farm staff, IRDF are superior to other feeding devices, because they are less labour-intensive than usual tasks. We conclude that IRDF is a useful feeding system for aquaculture

Survival and growth rates of Sutchi catfish (Pangasianodon hypophthalmus) juveniles under different light wavelengths and intensities

This study report the effects of light intensity on the optimum light wavelength and intensity on the survival rate, specific growth rate, and production index of sutchi catfish (Pangasianodon hypophthalmus, Sauvage, 1878) juveniles. The sutchi catfish juveniles (69 days old) with average initial body length of 5.14 cm and body weight of 1.11 g were reared for 11 days (20 individuals/30 L) under five light wavelengths (white with λmax 446 and 566 nm, blue 454 nm, green 520 nm, yellow 590 nm, and red 632 nm) with three light intensities (1.40×10-3, 1.40×10-2 and 1.40 μmol/m²/s) in triplicates. A twoway ANOVA analysis showed that light intensities had significantly (P < 0.05) affected the survival and specific growth rates of sutchi catfish juveniles. A Bonferroni post hoc analysis showed that the survival and specific growth rates were significantly high (P < 0.05) under the light intensity of 1.40 μmol/m²/s. In addition, there was a tendency of high growth rate, specific growth rate and production index under red light. Thus, the light intensity of 1.40 μmol/m²/s under red light is recommended for the rearing of sutchi catfish juveniles for better survival rate, growth rate and production index

The influence of light wavelength and intensity to the survival rates, growth rates and production index of Sutchi Catfish larvae

Sutchi catfish Pangasianodon hypophthalmus (Sauvage, 1878) is one of the most important freshwater fish species cultured in Southeast Asia. Artificial seed production of sutchi catfish is very important in aquaculture industry. However, the larval survival rates were low when reared in the hatchery. Providing optimum rearing condition for sutchi catfish larvae in the hatchery can increase the seeds production. Light conditions was reported to influence the survival and growth of fish. Hence, this study was conducted to examine the optimum light conditions in term of light wavelength and light intensity for rearing of sutchi catfish larvae. The sutchi catfish larvae were reared under five different light wavelengths (white, blue, green, yellow and red lights) and four different light intensities (1.40 10-4 , 1.40 10-3 , 1.40 10-2 , and 1.40 10-1 µmol/m²/s). The results showed that, the survival rates (SR), growth rates (SGRTL and SGRBW) and Production Index (PI) were higher in red light than other wavelengths. For light intensity, only PImshown significant effect to the larvae. Light intensity of 1.40×10-3 µmoles/m²/s wasmsignificantly higher than 1.40×10-1 µmoles/m²/s intensity. Apart from that, there weremtendency for high SR, SGRTL and SGRBW under low light intensities (1.40 10-4m and 1.40 10-3 µmoles/m²/s) when compared to high light intensities (1.40 10-2, and 1.40 10-1 µmol/m²/s). Therefore, red light wavelength and low light intensities (1.40 10- 4 and 1.40 10-3 µmoles/m²/s) were recommended when rearing sutchi catfish larvae

Determination of visual axis of tiger grouper juveniles Epinephelus fuscoguttatus, to develop a demand feeding system

In a demand feeding system, the fish turn on the switch of the feeder to get feed. In order to develop a demand feeding system with an infrared light sensor to which juvenile tiger grouper, Epinephelus fuscoguttatus visually respond, the visual acuity and visual axis of the juveniles were determined to obtain fundamental understanding of their vision. Three farmed juveniles were anaesthetized with MS222 and fixed in Bouin’s solution. The left retinae of each juvenile were cut into nine regions (Figure 1). The specimens were embedded in paraffin, cut into 6 μm thick tangential sections, and stained with haematoxylin-eosin. The density of cone cells (0.01mm2) in each region was counted in the stained sections. Visual acuity was calculated using cone cell densities and lens diameter. The highest cone density of each juvenile was 359 (bottom, B), 394 (temporal, T) and 380 cells/0.01mm2 (temporal, T) respectively. The estimated minimum separable angles of the highest density regions were 4.312×10-3, 3.661×10-3, 3.592×10-3 radian in each juvenile respectively. The estimated visual acuities were 0.068, 0.080 and 0.081 in those regions. These results showed that the visual axis of tiger grouper juveniles was in forward

Growth performance of brown-golden marine microalga, Isochrysis sp., cultivated in alternative algal culture media

The present study aimed to evaluate the suitability of introduced algal culture media as an alternative to the general enriched seawater media in the laboratory cultivation of Isochrysis sp., a marine microalga commonly cultivated for aquaculture purposes. Isochrysis sp. was established into culture in three replications using three experimental algal culture media (Walne’s medium as a control, China-contributed culture medium (CCM) and CCM supplemented with vitamins (CCM + Vit)). The experiment was performed with a continuous illumination for a period of seven days at 25±1°C. The effect of introduced algal culture media (CCM and CCM + Vit) on the growth performance of Isochrysis sp. was highlighted. CCM demonstrated promising results for the cultivation of Isochrysis sp. A maximum cell density of 9.16×106 ± 5.40×105 cells mL-1, which corresponded to an instantaneous growth rate (r) of 0.21 cell day-1 and a doubling time (T2) of 3.29 days, was observed in Isochrysis sp. cultivated in CCM. In view of its potential and reduced preparation labour, CCM may be recommended as an alternative to the general enriched seawater media in the cultivation of Isochrysis sp. in laboratories with basic facility as well as small- and medium-scale aquaculture hatcheries

Length-weight relationship and relative condition factor of pearl oyster, Pinctada fucata martensii, cultured in the Tieshangang Bay of the Beibu Gulf, Guangxi Province, China

Tieshangang Bay in the Beibu Gulf, Guangxi of China, is a strategic location for pearl farming. Although water pollution has been reported in this bay but the general health of the pearl oyster, Pinctada fucata martensii,farmed there has never been assessed. The present study examined the condition of P. fucata martensii farmed in the Tieshangang Bay by analyzing its length-weight relationship (LWR) and relative condition factor (RCF). A total of 111 specimens were sampled for measuring their shell height and total weight for determining the LWR and RCF. The coefficient of correlation of the LWR was high (R2= 0.93), significant at 0.01 level. Negative allometric growth (b= 2.7048) was observed. However, P.fucata martensiiachieved the expected growth in terms of weight, as determined through the RCF (mean 1.13). Negative allometric growth is commonly reported on the wild Pinctadaspp. collected from different regions. Apparently, the water pollution in the Tieshangang Bay did not compromise the general health of the pearl oyster cultured there. Nevertheless, further study on the farm’s surrounding water quality and plankton availability is necessary to investigate the interaction between the growth of the oyster and its culture environment. In conclusion, the P. fucata martensiifarmed in the Tieshangang Bay was considered healthy and the bay is still suitable for pearl oyster farming

High growth rate using new type demand feeding system with image processing program and fish behavior.

Demand feeding system serves feeds to fish, when fish switch on feeders. Although demand feeding system has advantages, it still has problems, e.g. hierarchy problem of fish school and system learning period problem for fish. New type of demand feeding system was develop to solve these problems using fish behaviour and image processing system. At first, behaviour experiment was conducted using the image processing software Roborealm to obtain the optimum parameter for computer program. Through the behaviour experiment, two typical behaviour patterns were detected. When fish was hungry, fish group came to the water surface (H: parameter >63%), and when fish was not hungry, fish came to bottom (L: <45%) of fish tank. These two parameters were obtained and were put into the computer program in the workstation. HD Wi-Fi camera continuously recorded the real time fish behaviour in fish tank, and when fish group came to above the “H”, then the command was sent from workstation to microcomputer to send the order to feeding device to feed on. The results of feeding experiment showed this system could provide pellets to fish day and night time equally following fish behaviour. This feeding system could provide the pellets to fish based on fish requirements. The growth rate was higher than other feeding system (timer feeder and demand feeder using an infrared light sensor)

Applications of multi-walled carbon nanotube in electronic packaging

Thermal management of integrated circuit chip is an increasing important challenge faced today. Heat dissipation of the chip is generally achieved through the die attach material and solders. With the temperature gradients in these materials, high thermo-mechanical stress will be developed in them, and thus they must also be mechanically strong so as to provide a good mechanical support to the chip. The use of multi-walled carbon nanotube to enhance the thermal conductivity, and the mechanical strength of die attach epoxy and Pb-free solder is demonstrated in this work

An Updated Search of Steady TeV γ−\gamma-Ray Point Sources in Northern Hemisphere Using the Tibet Air Shower Array

Using the data taken from Tibet II High Density (HD) Array (1997 February-1999 September) and Tibet-III array (1999 November-2005 November), our previous northern sky survey for TeV $\gamma-$ray point sources has now been updated by a factor of 2.8 improved statistics. From $0.0^{\circ}$ to $60.0^{\circ}$ in declination (Dec) range, no new TeV $\gamma-$ray point sources with sufficiently high significance were identified while the well-known Crab Nebula and Mrk421 remain to be the brightest TeV $\gamma-$ray sources within the field of view of the Tibet air shower array. Based on the currently available data and at the 90% confidence level (C.L.), the flux upper limits for different power law index assumption are re-derived, which are approximately improved by 1.7 times as compared with our previous reported limits.Comment: This paper has been accepted by hepn