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

Rearing of grouper juveniles using a demand feeding system with an infrared light sensor

Demand feeding is a new feeding method that fish can feed themselves. Fish switch on the feeding device when they require food. This method has several advantages because the fish can eat when they are most motivated to feed. The system can thus minimize feed loss and reduce water pollution. In this study, brown-marbled grouper Epinephelus fuscoguttatus and orange-spotted grouper Epinephelus coioides juveniles were reared using demand feeding devices using the commercialized and own developed demand feeders. Ten juveniles of each species were kept in a 500 L round polyethylene tank respectively (nine tanks, 90 fish). The tanks had water running system with water change (90%) every morning. Throughout the experiment, fish were exposed to natural photoperiod. Water temperature was 28.0 – 31.5 °C and salinity was 27-28 ppt. During rearing experiment, the fish were fed with pellets (Otohime EP3, Marubeni Nisshin Feed Co. Ltd.). Three experimental groups, pendulum demand feeder group (PDF, FH221, Aquatic Eco-Systems, Inc.), infrared sensor demand feeder group (IRDF) and automatic feeder group (AF) were set with three replicates. The IRDF consisted of an infrared sensor (infrared light 860 nm) ending in a red pellet-like knob with food container. Both demand feeders (PDF and IRDF) were set to dispense 10-15 pellets when fish activated the trigger (pendulum rod and infrared sensor respectively) located 2 cm below the water surface. We checked the fish circadian rhythm to determine the feeding time for the automatic feeder. The automatic feeder (AF) was set to dispense 150-170 pellets at 08:00 and 17:00 h. The experiment lasted for 25 days. Fish growth rates; total length (TL), and body weight (BW) were compared. Results of brown-marbled grouper juvenile experiments showed TL growth rates of IRDF group were significantly higher than that of PDF group (P<0.05), however, BW growth rates were similar among three groups. Results of orange-spotted grouper juvenile experiments showed no significant differences in TL and BW growth rates among three groups, but TL and BW of IRDF group showed higher tendency than that of AF and PDF groups

Demand feeding system using an infrared light sensor for Brown-marbled grouper juveniles, Epinephelus fuscoguttatus = Penggunaan sensor cahaya inframerah dalam sistem suapan permintaan untuk juvana Kerapu Harimau, 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. Secara umum, peranti suapan permintaan dilengkapi dengan suis pencetus mekanikal. Suis berkenaan tidak sesuai untuk ikan juvana bersaiz badan kecil kerana berat badan mereka tidak mencukupi untuk mengaktifkan peranti suapan. Sensor cahaya inframerah yang tidak memerlukan ikan untuk menolak suis peranti suapan adalah lebih sesuai untuk ikan bersaiz kecil. Kerapu harimau Epinephelus fuscoguttatus merupakan spesies ikan yang penting di Asia Tenggara. Tujuan kajian ini adalah untuk membandingkan kadar pertumbuhan (GRs) juvana kerapu harimau yang diternak menggunakan peranti suapan permintaan yang diterapkan dengan sensor cahaya inframerah (kumpulan suapan permintaan inframerah (IRDF)) dan peranti suapan automatik (kumpulan suapan automatik (AF)). Hasil kajian menunjukkan bahawa tiada perbezaan yang signifikan dalam GRs panjang piawai dan berat badan melalui analisis varians sehala; walau bagaimanapun, panjang piawai kumpulan IRDF menunjukkan adanya kecenderungan peningkatan GR berbanding kumpulan AF. Walaupun tiada perbezaan yang signifikan pada nisbah penukaran makanan (FCR), FCR kumpulan IRDF adalah lebih efisien dan ini menunjukkan bahawa kumpulan IRDF menghasilkan FCR yang lebih wajar. Hasil kajian ini menunjukkan bahawa IRDF boleh digunakan dalam penternakan juvana kerapu harimau. Apabila jadual kerja pekerja penternakan ikan diambil kira, IRDF adalah lebih baik berbanding peranti suapan yang lain kerana ia tidak memerlukan tenaga kerja yang ramai. Kami menyimpulkan bahawa IRDF adalah satu sistem suapan yang berguna untuk akuakultur

Optimum light conditions for eggs incubation and larval rearing of brown-marbled grouper Epinephelus fuscoguttatus

Optimum light condition is important factor to reduce fish stress and to increase growth rate under cultivating conditions. There are many studies about light intensities for larval rearing. However, there are only few studies about light wavelengths and light intensities for egg incubation and larval rearing. Brown-marbled grouper, Epinephelus fuscoguttatus is an important fish species for aquaculture in Southeast Asia. This study was conducted to examine the optimum light wavelength and intensity for brown-marbled grouper using light emitting diode (LED) lamps. Brown-marbled grouper eggs were obtained from the IIUM hatchery. The eggs were incubated in 40L aquarium in dark rooms, using broad spectrum white light (430-460<λ<500-630 nm) as a control, blue light (450-485 nm), green light (500-560 nm), yellow light (580-605 nm) and red light (610-650 nm). The eggs were incubated under 0.38, 1.7 and 8.7 µmoles/m²/s for each wavelength. Each condition was conducted in triplicate. The temperature was maintained at 27.5-28.5oC. The larval rearing experiments were also conducted under the same conditions. Larvae were sampled to examine the survival rate and growth rate. Nannochlropsis were added from 0 days after hatching (density; 1million cells/ml). Feeding was started at one day old. Results showed that hatching rates had higher tendency under short wavelength lights (blue and green) and survival rates of larval rearing also had higher tendency under short wavelength lights

The optimum light condition for Sutchi catfish larval rearing

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 the 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. The light condition was reported to influence the survival and growth of fish. Hence, this study was conducted to examine the optimum light condition in term of light wavelength and light intensity for sutchi catfish larval rearing. 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 PI showed a significant effect on the larvae. Light intensity of 1.40×10-3 µmol/m²/s was significantly higher than 1.40×10-1 µmol/m²/s intensity. Apart from that, there was a tendency for high SR, SGRTL and SGRBW under low light intensities (1.40×10-4 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 the optimum light condition for sutchi catfish larval rearing

Egg hatching rates of brown-marbled grouper, Epinephelus fuscoguttatus under different light wavelengths and intensities

This study was conducted to examine the egg hatching rates of brown-marbled grouper, Epinephelus fuscoguttatus under different light conditions in terms of light wavelengths and intensities. Results of two-way ANOVA showed significant difference for light wavelengths (p<0.05), while light intensities showed no significant difference. There was no interaction between light wavelengths and intensities. Post-hoc Tukey test showed that hatching rates under green light wavelength were significantly higher than white and yellow light wavelengths (p<0.05). When white light 2.7 μmoles/m²/s was set as the control, the hatching ratio of the brown-marbled grouper under green light 2.7 μmoles/m²/s was almost three times higher than the control. The lowest ratio of hatching rates was observed under the white light 13.3 μmoles/m²/s with 70 percent lower ratio of hatching rates than the control light. Eggs hatching under other light conditions mostly showed higher ratios than the control light

Comparison of Digital Elevation Model (DEM) from consumer grade drone with shallow-water bathymetry at Redang Island Marine Park, Terengganu

The most common method of obtaining shallow-water bathymetry usually by using single beam echosounder. Recent technology shows that consumer grade drone not only capable to capture aerial images, but also provide DEM of terrain and land area. However, there are less studies and information regarding shallow-water bathymetry derived from consumer grade drone DEM. Thus, this study compared the DEM produced by consumer grade drone with the bathymetry from Single Beam Echosounder (SBES) for shallow-water area in Redang Island Marine Park. The DJI Phantom 4 with Zenmuse X3 camera (RGB) have been used to obtain aerial images with elevation data. The drone fly with automated DroneDeploy application during a standardized time ranged between 8AM to 10AM and 4PM to 6PM, in order to avoid excessive sun glint. The bathymetry survey has been conducted using SBES Hummingbird 581iHD Down ImagingTM. The data from drone and SBES were processed into DEM using DroneDeploy Proprietary Map Engine and Hypack Max 2014. The DEM data from drone and SBES extracted at 24 transect locations and compared statistically. The result indicates the data at most shallow level (0m to -1m) have the highest value of R2 (0.3335) and lowest RMS error (0.082), in comparison with depth more than 1m. Therefore, the bathymetry derived from consumer grade drone DEM, based on RGB sensor is not suitable to be used for safety navigation mapping, especially for depth greater than 1m. However, it can be applied for other coastal study purposes, such as shoreline monitoring