Water quality in fish tanks is essential to reduce fish mortality. Many factors affect the water quality, such as pH, dissolved oxygen, and temperature in fish tanks. Existing work has presented water quality monitoring systems for aquaculture, which are useful for automatic monitoring and notify any incidence of decline in water quality. It enables the fish farms to make interventions to reduce fish mortality. However, advanced monitoring through forecasting is necessary to ensure consistent optimum water quality. This paper presents a web-based water quality monitoring and forecasting system for aquaculture. First, a water quality forecasting model based on the long short-term memory is designed and developed. The model is evaluated and fine-tuned using the existing public dataset. Second, the prototype of the water quality monitoring and forecasting system is developed. An Arduino and Raspberry Pi based water quality data acquisition tool is built. A web-based application is then developed to present the monitoring data and forecasting. A notification module is included to send an alert message to the fish farmers when necessary. The system is tested and evaluated at the fish hatchery in Universiti Malaysia Sabah. The findings show that the proposed system provides better water quality management for fish farms.

Marine microalgae may produce antibacterial substances. At the exponential phase of growth, four species of marine microalgae were examined for their potential to create secondary metabolites that limit the growth of Vibrio harveyi: Nannochloropsis oceanica, Chaetoceros gracilis, Isochrysis sp., and Thalassiosira weissflogii. V. harveyi is a pathogenic bacteria that can cause severe mortality and loss in aquaculture. Disc diffusion assay and co-culture assay were used to determine antibacterial activity. On TSA % NaCl media, the disc impregnated with microalgae and extracted with ethanol, methanol, saline water, and dimethyl sulfoxide (DMSO) was tested against V. harveyi at concentrations of 1.0 × 10⁵, 10⁶ and 10⁷ CFU mL⁻¹. The disc diffusion assay revealed that N. oceanica extracted with ethanol had the largest inhibitory zone against V. harveyi. Meanwhile, only N. oceanica, Isochrysis sp., and T. weissflogii reduced the growth of V. harveyi (10⁵ CFU mL⁻¹) in the co-culture assay (p < 0.05). The current findings reveal that the hydrophilic chemicals in microalgae extract have antibiotic activity against the highly virulent V. harveyi, which causes vibriosis, a serious disease in farmed fish and aquaculture cultivation around the world.

This study aims to reveal the first report of the natural spawning of F1 hybrid grouper (TGGG), a crossbreed between the tiger grouper, Epinephelus fuscoguttatus × giant grouper, E. lanceolatus, since its first production in 2006. This marks the completion of its full cycle after a 10-year period. In order to establish a seed rearing protocol for a novel F2 hybrid TGGG, natural spawning, embryonic and larval developments were thoroughly observed. Five batches of natural spawning were recorded with an average of 1.50–15.3 kg eggs collected, while fertilization and hatching rates were recorded at 85.3–97.6%, and 63.0–98.3%, respectively. F2 larvae hatched out at 17:50 hours with an average body size of 1.74 ± 0.01 mm, and a yolk sac volume of 0.85 ± 0.197 mm³. The first feeding was initiated 3 days after hatching, which coincided with the onset of functional feeding apparatus and active swimming behavior. Larval dorsal and pelvic spines were formed at 6 days AH coupled with dynamic feeding activity, as more food was found in the digestive tract. Meanwhile, the F2 hybrid grouper shifted habitat from pelagic to benthic as early as 25 days AH, and entered a juvenile stage at 35 days AH, attaining a skin coloration similar to that of the F1 juvenile. This study concluded that naturally spawned eggs of F2 hybrid TGGG were exceptionally high in quality, although larvae were small and fragile, and performed vigorous feeding activities and cannibalistic behavior. Thus, these findings can serve as primary data to further develop the optimal rearing protocol to enhance the overall rearing performance.

Marine aquaculture development is recently impeded by parasitic leech Zeylanicobdellaarugamensis (Hirudinea, Piscicolidae) in Sabah, Malaysia. The parasitic leech infests a variety of cultured fishes in aquaculture facilities. In this study, we evaluated the antiparasitic activity of the chromatographic fractions of the medicinal plant Nephrolepis biserrata methanol extract against Z.arugamensis and highlighted the potential metabolites responsible for the antiparasitic properties through liquid chromatography (LC)–quadrupole time-of-flight (QTOF)–mass spectrometry (MS) analysis. Out of seven fractions obtained through flash column chromatography techniques, three fractions demonstrated antiparasitic properties. Significant parasitic mortality was indicated by fraction 3 at a concentration of 2.50 mg/mL, all the leeches were killed in a time limit of 1.92 ± 0.59 min. followed by fraction 4 (14 mg/mL) in 34.57 ± 3.39 and fraction 5 (15.3 mg/mL) in 36.82 ± 4.53 min. LC-QTOF-MS analysis indicated the presence of secondary metabolites including phytosphingosine (6), pyrethrosin (1), haplophytine (9), ivalin (2), warburganal (3), isodomedin (4) and pheophorbide a (16), representing sphingoid, alkaloid, terpenoid, phenolic and flavonoid groups. Thus, our study indicated that the chromatographic fractions of N. biserrata demonstrated significant antiparasitic activity against the marine parasitic leeches due to the presence of potent antiparasitic bioactive compounds.

This study was aimed to identify the sex of humphead wrasse, Cheilinus undulatus kept in captivity based on body sizes and morphological characteristics. There were 65 tails of C. undulatus broodstocks reared in the captivity throughout six months of research period and fed daily with enrich prey fish (Sardinella sp.). Growth parameters and morphological characteristics such as presence of eyeline, hump on head and genital papillae, of the C. undulatus were carried out. These findings revealed in captivity, female of C. undulatus (n=13) attained an average body weight of 2.78 kg and total length 47.10 cm meanwhile male of C. undulatus attained larger body weight (14.62 kg) and total length exceeding size of female (89.30 cm). C. undulatus performed an isometric growth pattern (b = 2.9487) with condition factor of above 0.2. Morphologically, female was identified with the noticeable alleviation of the hump on its head and the visibility of eyeline behind its eyes which was not seen in male. This study concluded sex of C. undulatus in captivity is differentiated through body size and morphological features and take longer time in sex transition, thus balanced sex ratio for good broodstock management can be controlled to develop appropriate breeding protocol.