Growth performance and gonad maturation of amur catfish, silurus asotus in captivity

This study was aimed to determine the growth performance and gonad maturation of Amur catfish, Silurus asotus reared in captivity. A total of 600 juvenile Amur catfish were reared in a 20-tonne aerated fibreglass tank for 3 months. The changes to body weight (mean ± SD) of Amur catfish at day 14 was 22.59 ± 3.59 g and attained a final average body weight of 110.95 ± 19.72 g. The average body weight gains (%) were 213.50% and gradually decreased to 109.95%. The specific growth rate recorded at 14-day intervals was 5.42%/day and fluctuated to 3.32%/day, 0.39%/day, 0.51%/day, with the corresponding measurements of 15.36 ± 1.07 cm and increments to 24.22 ± 1.34 cm. The final total length the fishes attained was an average of 25.58 ± 1.95 cm. The total length gain recorded was 124.61% and followed by 109.95%. The survival of Amur catfish within the three months was 29.17%. Length-weight relationship of the Amur catfish showed a strong correlation at log W =-2.6797 + 2.3102 log L and the value of the regression coefficient (b) equalled to 2.3102. Three stages of the oocyte (PO = primary oocyte, PVO = previtellogenic oocyte and VO = vitellogenic oocyte) determined histologically indicated that all-female gonad samples were in the developing stage. Matured gonad and spermatozoa were also observed in males. This study concludes that Amur catfish attained good growth performance and fast gonad maturation in captivity and can be a suitable species for aquaculture

Effects of long jack, Eurycoma longifolia on sperm quality and quantity of African catfish, Clarias gariepinus

The experiment attempts to study the effects of long jack, Eurycoma longifolia through the sperm quality and quantity of African catfish, Clarias gariepinus. Mostly farmers are using hormone to induce the reproduction in these fishes especially C. gariepinus. For expanding demand in C. gariepinus, there was expanded exertion in the improvement of method for production of fish in hatchery. Thus, this study was an alternative to improve the production of C. gariepinus. In the present study, two diets with crude protein of 40 % were formulated with different supplementation levels of E. longifolia powder; with no supplementation of E. longifolia (LJ0) and the supplementation of 5 % E. longifolia (LJ5). Eight males of C. gariepinus were randomly distributed into two fibre tanks (2×2×1.5 m) with four fish per tank. The tank contained green water (pH≈ 7.2, dissolved oxygen≈ 5.3 mg/L, temperature≈ 27.20°C). C. gariepinus were fed at 3% of body weight twice a day for a period of 30 days.The diet in LJ5 had significantly higher in sperm counts (12085.33±286.71x104 sperm/ml), milt volume (0.38±0.04 ml) and motility duration (24.11±0.96sec). While the result for diet in LJ0 in sperm count, milt volume and motility duration were 10014.67±273.76x104sperm/mL, 0.21±0.06 ml and 12.67±0.58sec.However, significant differences were not observed in the body weight gained, total length, specific growth rate and feed conversion ratio (FCR) among the two treatments. Besides, the results showed that E. longifolia possess promising pro-fertility which can be exploited in fish seeds production and 50 g/kg of E. longifolia based diet could give satisfactory and efficient result on the sperm quality and quantity of C. gariepinus

Growth Performance and Gonad Maturation of Amur Catfish, Silurus Asotus In Captivity

This study was aimed to determine the growth performance and gonad maturation of Amur catfish, Silurus asotus reared in captivity. A total of 600 juvenile Amur catfish were reared in a 20-tonne aerated fiberglass tank for 3 months. The changes to body weight (mean ± SD) of Amur catfish at day 14 was 22.59 ± 3.59 g and attained a final average body weight of 110.95± 19.72 g. The average body weight gains (%) were 213.50% and gradually decreased to 109.95%. The specific growth rate recorded at 14-day intervals was 5.42%/day and fluctuated to 3.32%/day, 0.39%/day, 0.51%/day, with the corresponding measurements of 15.36 ± 1.07 cm and increments to 24.22 ± 1.34 cm. The final total length the fishes attained was an average of 25.58 ± 1.95 cm. The total length gain recorded was 124.61% and followed by 109.95%. The survival of Amur catfish within the three months was 29.17%. Length-weight relationship of the Amur catfish showed a strong correlation at log W = -2.6797 + 2.3102 log L and the value of the regression coefficient (b) equaled to 2.3102. Three stages of the oocyte (PO = primary oocyte, PVO = previtellogenic oocyte and VO = vitellogenin oocyte) determined histologically indicated that all-female gonad samples were in the developing stage. Matured gonad and spermatozoa were also observed in males. This study concludes that Amur catfish attained good growth performance and fast gonad maturation in captivity and can be a suitable species for aquaculture

Successful co-feeding of Asian seabass, Lates calcarifer larvae with palm oil-based microdiets and live feeds

Palm oil has been recognized as a high potential alternative dietary lipid source to reduce the reliance on expensive fish oil in aquaculture feeds. Unfortunately, most research studies were focusing on the juvenile or grow-out stage of aquatic species. This study was designed to develop weaning microdiets for Asian seabass larvae with dietary fish oil being replaced with crude palm oil (CPO) at 25, 50, and 75% (CPO25, CPO50, and CPO75) and refined bleached deodorized palm olein, refined palm oil (RPO) at 50 and 75% (RPO50 and RPO75) replacement levels. A fish-oil-based microdiet was used as a control treatment (FO100). The triplicate groups of fish larvae with initial weight and length of 1.71 ± 0.13 mg and 5.54 ± 0.34 mm, respectively, were stocked at 150 larvae/tank and co-fed with the experimental microdiets and live feeds (L-type rotifer and artemia). The final body weight (0.54–0.63 g) and specific growth rate (SGR) (12.8–13.13%/d) of fish-fed palm oil-based diets were significantly better than the control diet (0.42 g; 12.21%/day, respectively). In particular, RPO75 yielded the best SGR followed by RPO50, CPO75, CPO50, and CPO25. The feeding intake and feed conversion ratio (FCR) were not statistically different from other treatments (0.2–0.3 g/fish/d and 1.06–1.63, respectively). The survival rate of larvae-fed palm oil-based diets (33.11–46.67%) during the feeding trial was comparable to the control diet (39.33%). In the 65 ppt-salinity stress test at 25 DPH, there was no significant difference in terms of the survival rate of larvae fed the control diet and the CPO-based diets, but the lowest survival rate was observed in the RPO-based diets than the control diet. Higher final whole-body protein and lipid contents (15.3 ± 0.4 and 3.7 ± 0.0%, respectively) were observed in fish-fed CPO50 compared to other treatments. Generally, the replacement of fish oil with palm oil increased the palmitic acid (C:16:0) and oleic acid (C18:1n9) and significantly reduced the eicosapentaenoic acid (EPA) (C20:5n3) and docosahexaenoic acid (DHA) (C22:6n3) contents in both the microdiets and larval body, a common observation in this kind of investigation. Considering the good growth and survival of Asian seabass larvae in this study, availability of palm oil, and its competitive price compared to fish oil, it is suggested that weaning diets for Asian seabass larvae can be developed using palm oil as a partial source of dietary lipid

Development of sensory organs and changes of behaviour in larvae Amur catfish, Silurus asotus

The development of morphology, sensory organs, and behavioural changes in larvae of Amur catfish (Silurus asotus) were described from 0 h after hatching (hAH) to 20 days after hatching (dAH) reared at 26.7 ± 1.3 °C under controlled conditions. The newly hatched larvae (4.71 ± 0.87 mm) had eyes that were only outlined and unpigmented, no taste buds, and free neuromasts with a demersal swimming mode associated with negative phototaxis and immediate rheotaxis responses. At 12 hAH (5.57 ± 0.25 mm), larvae had pigmented eyes, exhibited initial vertical and horizontal swimming behaviour, and switched to positive phototaxis and positive immediate rheotaxis responses. At 30 hAH (7.01 ± 0.41 mm), larvae with well-developed sensory organs began feeding for the first time, and cannibalistic behaviour was noted for the first time at this stage. At 5 dAH (12.12 ± 0.68 mm), larvae had enlarged taste buds and free neuromasts associated with active swimming behaviour. At 12 dAH (20.22 ± 0.09 mm), the Amur catfish entered the juvenile stage, and at 20 dAH (34.10 ± 0.89 mm), a pair of mandibular barbels degenerated and the fish preferred to remain on the substrate. This study concludes that the development of Amur catfish larval morphology, sensory organs, and behaviour are interrelated and progressively developed as larvae age

Egg development of backgrossed hybrid grouper between OGGG (Epinephelus coioides x Epinephelus lanceolatus) and giant grouper (Epinephelus lanceolatus)

The hybrid grouper, OGGG is produced from a cross-breed between a female orange-spotted grouper (OG; Epinephelus coioides) and a male giant grouper (GG; E. lanceolatus). OGGG is an excellent hybrid grouper in Southeast Asia owing to its outstanding organoleptic qualities. GG is the most favorable species in aquaculture industry driven by its notable characteristics. With the purpose of producing a superior aquaculture species, a backcross-breed between OGGGs and GGs was conducted. A sexually matured female OGGG was selected and treated twice with Human Chorionic Gonadotropin (HCG). Subsequently, the stripped eggs were fertilized with preserved sperm of GG and incubated in a circular fiberglass reinforced plastic (FRP) tank. Observation on stripped eggs, egg development and developed time on each egg stage was recorded under microscope. The fertilized eggs were spherical with a mean diameter of 755 ± 28 µm (n = 20). The fertilization rate and hatching rate were 23.3 % and 1.5 %, respectively. The hatching time was commenced from 22:40 to 24:40 hours after hatching (hAF). It was undergone normal egg development and successfully survived up to 11 dAH. It is possible to produce backcrossed OGGG and GG and beneficial to the production of hybrid grouper in aquaculture industry

Traumatic neck injury: An accidental impalement by a Needlefish

Encounters between marine animals and humans can result in critical injury and fatal complications. We highlight a 20-y-old male who sustained a penetrating injury to the neck as a result of impalement by needlefish (Tylosurus sp) while snorkeling. He sustained a penetrating injury in the posterior triangle of the neck. On presentation, he was stabilized and received empirical antibiotics, analgesia, and anti-tetanus toxoid injection before being transferred to a tertiary center. On presentation to the tertiary hospital, the patient was hemodynamically stable with no clinical evidence of injury to surrounding neck structures, and this was confirmed using computed tomography. The patient underwent local wound exploration and retrieval of the needlefish beak under general anesthesia. The wound was left open to heal by secondary intention. The patient was discharged with oral antibiotics and went on to make a complete recovery

Water temperature and stocking density for long-hour transportation of hybrid grouper Epinephelus fuscoguttatus x E. lanceolatus

This study aims to investigate the effect of water temperature and stocking density in a longhour transportation of hybrid grouper [tiger grouper (Epinephelus fuscoguttatus) x giant grouper (E. lanceolatus)]. A factorial design of three different water temperature levels (16, 18 and 21°C) and three different stocking density levels (120, 180 and 240 g L-1) was tested in this experiment. The experiment was conducted using a 10 L rectangular aquarium, equipped with a water chiller and aeration to maintain the water temperature at the required level. The hybrid grouper (average body weight: 5.11±0.34 g) were placed in each aquarium with different stocking density levels for a 12-hour period. The results show that the survival of fish was significantly lower (p < 0.05) at a lower water temperature level (16°C; 50.2%), while there is no significant difference for the other temperature levels considered, 18 and 21°C. The results also show that the lowest water temperature had a significantly (p < 0.05) lower pH value in each stocking density. The glycogen content in fish liver was significantly higher (p < 0.05) at a low water temperature and low stocking density. A similar trend can be observed on the dissolved oxygen of water during the experiment. Moreover, the ammonia concentration was significantly (p < 0.05) higher at a higher water temperature and a higher stocking density. The findings in the present study suggest that hybrid grouper can be economically transported for a long hour journey at a high stocking density (240 g L-1), with a water temperature level between 18 to 21°C

Antiparasitic potential of a medicinal plant flower against marine parasitic Leech in aquaculture

The aquaculture industry is essential for food production and economic development in Malaysia and other parts of the world. The development is affected by the parasitic infestation on different cultured fish species. The most common marine parasitic leech Zeylanicobdella arugamensis (Hirudinea), which infests various cultured fishes in Malaysia, also in Southeast Asian countries. The current research aimed to elucidate the methanol extract of the flower of Dillenia suffruticosa (DS) belonging to the family Dilleniaceae as a natural control agent against marine parasitic leech Z. arugamensis. The leeches were collected from infested hybrid groupers in aquaculture facilities and challenged with various concentrations (25, 50 and 100 mg/ml) of the methanol extract of DS flower. The results demonstrated significant antileech activity against Z.arugamensis with total mortality in an average period of 53.77 ± 1.42, 37.63 ± 5.35 and 7.51 ± 0.74 min, respectively. Thus, the research displayed that the methanol extract of DS flower can act as a natural control agent against marine parasitic leech. The study will benefit fish farmers in Malaysia and other Southeast Asian countries to control the leeches using natural products

In vitro antibacterial activity of marine microalgae extract against vibrio harveyi

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