Trichogaster Pectoralis Research Articles

Changes in Water Quality and Soil Property in the Rice–Freshwater Animal Co-Culturing System

This study investigated the effects of integrating various fish species in a rice field co-culture system on water quality and soil properties. The species included common carp (Cyprinus carpio), Nile tilapia (Oreochromis niloticus), silver barb (Barbonymus gonionotus), snakeskin gourami (Trichopodus pectoralis), and giant freshwater prawn (Macrobrachium rosenbergii). The key water quality parameters measured included water temperature, dissolved oxygen, pH, transparency, ammonia, and nitrite. Soil properties were evaluated through pH, electrical conductivity, organic matter, nitrogen, phosphorus, and potassium. All the selected aquatic animals showed high adaptability in co-culture systems, with survival rates exceeding 80%. Additionally, rice yields increased by approximately 16%, with the highest yield observed in plots stocked with prawns. The results indicated that the presence of aquatic animals enhanced nutrient cycling, leading to significant improvements in both water quality and soil fertility. Differences in water quality and soil properties throughout the culture period were specific to the species present. These findings suggest that rice-fish co-culture systems serve as an effective nature-based solution for enhancing productivity, sustainability, and food security.

Whole genome sequence and characterisation of Streptococcus suis 3112, isolated from snakeskin gourami, Trichopodus pectoralis

BackgroundStreptococcus suis (S. suis) is an important swine and human pathogen. A recent study reported the first isolate of S. suis capable of infecting fish, designated as S. suis strain 3112. The bacterium was isolated from snakeskin gourami (Trichopodus pectoralis), an economically important fish species native to Southeast Asia, and it was previously shown that it can infect and cause lethal streptococcosis in the fish.ResultsIn this study, we present the complete genome of S. suis 3112. Molecular sequence analysis revealed that it belongs to serotype 6, sequence type 2340. Phylogenetic analysis showed that the bacterium clustered with healthy-pig S. suis isolates, suggestive of an ultimate swine (as opposed to human) origin of the bacterium. Two fluoroquinolone resistance genes are present in the bacterial genome, namely patA and patB. Our results showed that both genes are expressed in our bacterium, and the bacterium is resistant to norfloxacin, but is still sensitive to other fluoroquinolones, including ciprofloxacin, enrofloxacin, and sparfloxacin. Additionally, the bacterium is sensitive to β-lactams, tetracyclines, sulphonamides, and an aminoglycoside.ConclusionsThis study reports and describes the complete genome of S. suis 3112, the first isolate of S. suis known to infect fish, and provides further insights into the bacterial isolate, particularly regarding its drug resistance profile. These results will facilitate further investigations of the comparative genomics and pathogenic characteristics of S. suis, as well as the development of control strategies against this newly-identified fish pathogen.

Effect of stocking density of Snakeskin gourami (Trichopodus pectoralis) in polyculture system with Black apple snail (Pila polita)

The experiment determined the effect of stocking density of snakeskin gourami in the polyculture model with black apple snails. The experiment included four treatments corresponding to four densities of fish (ind./m2): (i, Control): 0, (ii) 3, (iii) 5, and (iv) 7; snails were stocked at 150 snails/m2; each treatment was triplicated. The initial fish’s weight was 12 ± 0.3 g, and the snail’s weight was 0.15 ± 0.01 g. After 120 days of the experiment, the survival rate of fish was 100% in all treatments, whereas the survival rate of snails ranged from 80.22 to 82.44%, and there were no significant differences (p>0.05). Snails in the control treatment obtained the highest specific growth rate (2.68 %/day) and productivity (0.54 kg/m2). In contrast, the specific growth rate and productivity of fish obtained the highest number in treatment iv, with 0.98 %/day and 0.24 kg/m2, respectively. The highest profit was recorded in the treatment with 7 fish/m2, and this was significantly different (p<0.05) compared to the control and 3 fish/m2 treatment. Results from this study showed that the stocking density of 5 fish/m2 was suitable to enhance productivity of both snail and snakeskin gourami in polyculture system.

Streptococcus agalactiae Associated with "Dark Body" Disease on Snakeskin Gourami Farmed in the Mekong Delta, Vietnam

Streptococcosis, due to Streptococcus agalactiae, has become a serious challenge for aquaculture around the world. Therefore, the main purpose of this work was to confirm the etiological agent that caused "dark body" disease in snakeskin gourami (Trichogaster pectoralis) cultured in the Mekong Delta, Vietnam. Infected fish displayed clinical signs, including anorexia, lethargic swimming on the water surface, corneal opacity, and hemorrhage in the base of the fin. Remarkably, abnormal black coloration on the body and serious hemorrhage at the base of the pectoral fin, and on the body were found in infected fish. In total, 75 bacterial strains were isolated from different diseased fish farms. Based on morphological and physiological characteristics, the API 20 Strep test, and 16S rRNA sequence analysis, the result illustrated that the bacterial isolates were identified as S. agalactiae. Additionally, antibiotic sensitivity testing revealed that all the S. agalactiae isolates were sensitive to amoxicillin, rifampicin, clarithromycin, erythromycin, doxycycline, cephalexin, novobiocin, and sulfamethoxazole-trimethoprim. Interestingly, S. agalactiae strains were only resistant to gentamycin in this study. Two strains, SRT41 and SRT43, carried out an experimental challenge with concentrations from 104 to 107 CFU/ml in healthy snakeskin gourami, and the LD50 values of the isolates, SRĐT41 and SRĐT43, were determined to be 2.15 × 105 and 3.59 × 103 CFU/ml, respectively, after 7 days. To our knowledge, this is the first report of S. agalactiae derived from intensively cultured snakeskin gourami in the Mekong Delta, Vietnam.

Effects of dietary supplementation of estradiol-17β during fry stage on growth, physiological and immune parameters and gonadal gene expression in adult snakeskin gourami.

In snakeskin gourami (Trichopodus pectoralis), females are generally larger than males, and estradiol-17β (E2)-sex reversal to produce female monosex has gained interest in this species. In this study, we aimed to investigate the effects of E2-induced sex reversal on growth, physiological and immune parameters, and gonadal gene expression in adult snakeskin gourami. Fry (7days posthatching) were divided into different experimental groups based on the dose of E2: control (no E2 (0mgkg-1) supplementation), E2-100 (100mgkg-1), E2-200 (200mgkg-1), and E2-300 (300mgkg-1), fed with the E2 doses for 90 d and cultured for 11months (adult stage). The findings revealed that E2 supplementation produced 88.89-100% of female population. After 11months of culture, the effects of sexual dimorphism on the growth performance of the E2-100 group were not significant compared to that on the growth performance of the control male and female groups; however, it improved significantly in the E2-200 and E2-300 groups (P<0.05). E2 elevated the CP and fat contents in body in E2-200 and E2-300 groups (P<0.05) compared to that in the control group. No sex differences in blood metabolites, haematological values, or immune parameters were identified. Nevertheless, E2-200 and E2-300 groups showed increased blood glucose, triglyceride, haemoglobin, and total immunoglobulin (P<0.05) compared to control male fish. In addition, all concentrations of E2 increased alternative complement 50 (P<0.05). Several genes, including bHLH, cyp19a1, daz, deadend, esrb, esrrg, gnrhr, gpa, gsg1l, hsd17β, mospd1, nanos2, p53, piwi2, rerg, rps6ka, tgfb, and vgr, showed differential expression between testis and ovary in control female and E2-treated groups. The expression patterns of the genes were similar in the ovary of the control female and E2-200-treated fish. In conclusion, the findings demonstrate that a feminisation duration of 7-97days and two doses of E2 at 200 or 300mgkg-1 successfully produced all-female stocks in snakeskin gourami. Furthermore, the findings showed that E2-treated females were maintained throughout adulthood and exhibited several superior characteristics to male fish. Together with the information generated on differentially expressed sex-related genes, these findings could enable the culturing of faster-growing sex to increase productivity and contribute to the development of intensive snakeskin gourami farming.

Pathological effects due to metacercariae of Clinostomum piscidium migration in snakeskin gourami (Trichopodus pectoralis) in Thailand.

Clinostomum spp. is a fish-borne pathogen and a digenetic trematode with a global range. Despite its zoonotic relevance, the pathogenic impact of the parasite in Thai aquaculture is currently unclear. The present study deals with the pathogenic changes that fluke causes in their host, Trichopodus pectoralis, and the molecular confirmation of the Clinostomum piscidium by targeting 18 s rDNA and ITS gene. The metacercariae of C. piscidium were discovered in the body cavity of infected fish. The gross pathological examination revealed a few white migratory tracks on the surface of the liver and spleen. The migratory track showed histologically as a primary hemorrhage and necrosis of hepatic cells surrounded by a layer of macrophages and epithelioid cells, inflammatory cells, and eosinophilic granular cells in the cytoplasm of liver cells and close to the epithelial cells of the intestine. Also, the migratory track in the spleen appeared as a marked decrease of Red Blood Cell (RBC) count and changes in the necrotic tissue. Infection with this metacercaria produced hepatic tissue injury, which disrupted hepatic metabolism and decreased body weight in the fish hosts. The findings of the study suggest that the pathological effect of C. piscidium on farm T. pectoralis can cause significant economic loss by stunting fish development and predisposing fish to opportunistic pathogens in the environment. Hence, the treatment and control of C. piscidium infections are crucial for the viability of the aquaculture sector since this parasite has been found to cause pathological damage to the vital organs of fish.

Lumpy skin disease of snakeskin gourami: A new record of metacercariae of Posthodiplostomum sp. (Digenea, Diplostomidae) in clinically sick snakeskin gourami, Trichopodus pectoralis Regan, 1910 (Pisces, Osphronemidae)

Here, we report on two cases of disease with scattered, pronounced sub-epithelial swellings in the body of cultured snakeskin gourami (Trichopodus pectoralis) fingerlings from two independent farm sites. Locally, the condition is known colloquially as “lumpy skin disease”. The abnormal raised distortions of the skin were due to encysted metacercaria beneath the skin and deeper, within the subcutaneous musculature. Host reaction resulted in a thick, colourless, opalescent wall of the parasitic cyst. Excysted specimens were identified as metacercariae belonging to the genus Posthodiplostomum (Digenea, Diplostomidae) based on a combination of morphology and molecular analysis. Phylogenetically, using SSU rRNA genes, the isolate formed an independent cluster with other unnamed species Posthodiplostomum sp. from snakeheads (Channa spp.) reported from Japan and India; all the parasites in this group had metacercarial cysts with no or few melanophores. The development of parasite cysts resulted in pronounced skin distortions in cultured fingerlings and may be associated with the consequential high rates of morbidity and mortality. This case study is the first report of Posthodiplostomum sp. metacercariae in snakeskin gourami, adding to the growing range of host species infected with the genus. The severity and mortality associated with infection, however, requires further investigation together with a need to identify the precise species present.

Streptococcus agalactiae Serotype VII, an Emerging Pathogen Affecting Snakeskin Gourami (Trichogaster pectoralis) in Intensive Farming

Snakeskin gourami (Trichogaster pectoralis) is a freshwater fish species that is being increasingly cultivated in Southeast Asia. The expansion of farms and intensive farming practices has led to the unexplained mortality of snakeskin gourami and tremendous economic losses in many farms. We investigated the unusual mortality of snakeskin gourami at 22 farms in Central Thailand. The moribund fish showed darkened skin, erratic swimming, exophthalmos, and haemorrhaging around the eyeballs, with cumulative mortality between 20% and 45%. Our necropsy findings revealed an enlarged liver and anterior kidney, splenomegaly, haemorrhage in most internal organs, pericarditis, and brain congestion. Histopathology revealed haemorrhaging and congestion of the blood vessels in the liver with infiltration of lymphocytes, enlarged blood vessels with mononuclear and lymphocyte infiltration in the meninges, and cerebral parenchyma were observed. Severe necrotising and suppurative pericarditis with myocardial infarction were found. Epidemiological studies and laboratory diagnosis revealed that Streptococcus agalactiae was predominantly isolated from the moribund fish. Laboratory investigations of the representative 33 isolates of S. agalactiae using mass spectrometry, multiplex polymerase chain reaction assay, pulse-gel electrophoresis, and serotyping suggested that all the isolates were S. agalactiae serotype VII, which is different from the serotype III isolated from diseased tilapia in Thailand. An experimental challenge using three representative isolates of S. agalactiae on snakeskin gourami caused clinical signs, gross lesions, and pathological changes, with high mortality exceeding 60%, which is similar to the mortality in most natural infections. Moreover, S. agalactiae was recovered from the spleen, kidneys, and liver of all the challenged fish. Taken together, this study provides important information that S. agalactiae serotype VII is virulent in snakeskin gourami and can potentially spread among these fish in fish farms. Appropriate preventive measures and the control of animal movements should thus be implemented.

Behavior and swimming performance of local fish in the ecosystem waters of rivers, oxbow and peat swamps

The four fish species, Trichogaster pectoralis, Barbodes schwanenfeldii, Osphronemus gouramy, and Wallago leeri have the same body size, representing different habitats. Therefore, this study aimed to determine the four species swimming abilities and speeds, including sustained, maximum sustained, prolonged swimming speed, and burst speed. The four species were brought using oxygenated plastic bags to the Aquatic Resources Utilization Laboratory at Riau University. Then it was acclimated in an aquarium measuring 100×50×50 cm with an aeration and filtering system to maintain water quality. The four groups of species were forced to swim in the swimming channel of the flume tank, with different current speeds for each individual tested. The swimming activity of the fish was recorded using a high-speed video camera (Casio HS Exlim, EX-ZR400, Casio Computer Co. LTD, Japan). The results showed that the swimming speed of B. schwanenfeldii was higher than O. gouramy, T. pectoralis, and W. leeri. The maximum sustained swimming speed of B. schwanenfeldii is about 5.1 BL/s, and 14.2 BL/s for the burst speed. Meanwhile, the sustained swimming speed of O. gouramy (1.6 BL/s) and the burst speed is 7.2 BL/s. The maximum sustained swimming speed of T. pectoralis was 1.6 BL/s, and the burst speed was 5.7 BL/s. In addition, the maximum sustained swimming speed of W. leeri is only 0.5 BL/s and 2.4 BL/s for the burst speed. The ability of these four fish to swim was influenced by the morphology of the tail fin, body shape, and the habitat where they live.

Domestication of Snakeskin Gourami (Trichopodus pectoralis Regan, 1910) in Indonesia: Characterization, Bioreproduction and Early Development

Domestication of Snakeskin Gourami (Trichopodus pectoralis Regan, 1910) in Indonesia: Characterization, Bioreproduction and Early Development

Bioecological Aspects of Snakeskin Gourami (Trichopodus pectoralis) in the Flooded Swamp Waters of Bilah River, Labuhanbatu Regency

Background: The potential fish resources of snakeskin gourami (Trichopodus pectoralis) in the flooded swamp waters of Bilah river, Labuhanbatu Regency, are pretty high. Thus, this is one of the essential resources and has economic value. This study aimed to inform the bioecological aspects of snakeskin gourami fish (T. pectoralis). Methods: The determination of 3 sampling points was done using the purposive random sampling method. The sampling of T. pectoralis was carried out using the trap. The data analysis presented information on the abundance of Gonad Maturity Level, growth pattern, the Fulton (K) factor condition, and the Pearson correlation among environment parameters to the T. pectoralis population, which was presented quantitatively. Results: The results showed the length-weight relationship of T. pectoralis in the allometric category. The average relative weight (Wr) for male T. pectoralis was 100.46 ± 8.37, and for females was 99.83 ± 2.30. The mean value of the Fulton’s (K) factor condition in male T. pectoralis (8.94 ± 0.54) and female T. pectoralis (9.27 ± 0.67). Conclusions: T. pectoralis showed an allometric category and domination of the first gonadal maturity level. It describes that the female is abundant in optimum condition and ensures for future generations, and Pearson’s correlation result informs that increasing the value of environmental parameters will affect the optimization of T. pectoralis life.

Characterization of ddx4 and dnd Homologs in Snakeskin Gourami (Trichopodus pectoralis) and Their Expression Levels during Larval Development and in Gonads of Males and Females.

The purpose of this study was to clone and characterize ddx4 and dnd1 homologs in snakeskin gourami (Trichopodus pectoralis) and to determine their expression levels during larval development and in the gonads of males and females. Both cDNAs contained predicted regions that shared consensus motifs with the ddx4 family in teleosts and the dnd family in vertebrates. Phylogenetic tree construction analysis confirmed that these two genes were clustered in the families of teleosts. Both ddx4 and dnd1 mRNAs were detectable only in the gonads, particularly in germ cells. These two genes were expressed during early larval development. The expression of ddx4 was high during early larval development and decreased with increasing developmental age, whereas dnd1 expression increased with developmental age. In adult fish, the expression levels of both genes were higher in the ovary than in the testis. Overall, these findings provide valuable molecular information on ddx4 and dnd, and can be applied in future reproductive biological studies relating to sex dimorphism in snakeskin gourami.

Growth of Sepat Siam fish in flood swamps, South Sumatra

Sepat Siamese fish (Trichogaster pectoralis) is a swamp fish that is generally black or dark in color which is often called black fish. The South Sumatra area is famous for its many swamp areas. It is a flooded swamp and a suitable habitat for the Siamese sepat fish. Estuary Belida River, especially Kayu Ara Batu Village, is a flooded swamp area where many catches are found, namely Sepat Siam fish. Sepat Siam is a fish that has economic value and is very common throughout the year. The study was carried out 2021 in March, April, May, June, and July in Kayu Ara Batu Village. Fish samples come from the catches of fishermen who are sold to collectors, then measured the length and weight of 3037 Sepat Siam fish, and then analyzed using FISAT II Analysis. The purpose of this study was to determine the growth of Sepat Siam fish in swamp waters, especially swamp waters in Kayu Arabatu village. The results obtained are the infinitive length of the sepat fish is 45.68 with a value of K = 0.090, M = 0.33, Z = 0.35. F=0.02 and E= 0.06. Thus, the exploitation is still smaller than the optimum exploitation value so that the fish catch is still good and has not been included in the overfishing but is still in the controlled category.

Hubungan panjang berat dan faktor kondisi ikan sepat (Trichogaster pectoralis) di Perairan Rawa Desa Lakea Dua Kabupaten Buol Sulawesi Tengah

This study aims to determine the relationship between length and weight and condition factors of Trichopodus trichopterus in the waters of Rawa, Lakea Dua Village, Buol Regency, Central Sulawesi. The research was carried out for 2 months and took place in the swamps of Lakea Dua Village, Buol Regency, Central Sulawesi. The fish collected were measured based on the total length using a ruler in cm (1 mm accuracy), while the fish weight was measured using a digital scale with units of grams (0.01 gram accuracy). The test parameters observed included analysis of length and weight, relative weight, fulcon condition factor, and relative condition factor. The results showed that there were 53 Trichopodus trichopterus collected in the swamps of Lakea Dua Village, Buol Regency. The length ranges from 10-18 cm with an average length of 14.43±2.39 cm. Fish weight ranged from 14.50-155.30 g with an average weight of 51.33±25.83 g. The growth pattern is negative allometric. The relative weight shows a value of 102.63±21.40, meaning that the source of feed is abundant in the Trichopodus pectoralis environment and the condition is healthy. The Fulcon condition factor value is 1.61±0.55 and the relative condition factor is 1.04±0.33, meaning that the condition factor value is below 3. This shows the cheek-shaped fish. Keywords: condition factor; length weight; Trichogaster pectoralis

Length-weight relationship and condition factors of Trichogaster pectoralis in the swamp, Lakea Dua Village, Buol Regency, Central Sulawesi

This study aims to determine the relationship between length and weight and condition factors of Trichopodus trichopterus in the waters of Rawa, Lakea Dua Village, Buol Regency, Central Sulawesi. The research was carried out for 2 months and took place in the swamps of Lakea Dua Village, Buol Regency, Central Sulawesi. The fish collected were measured based on the total length using a ruler in cm (1 mm accuracy), while the fish weight was measured using a digital scale with units of grams (0.01 gram accuracy). The test parameters observed included analysis of length and weight, relative weight, fulcon condition factor, and relative condition factor. The results showed that there were 53 Trichopodus trichopterus collected in the swamps of Lakea Dua Village, Buol Regency. The length ranges from 10-18 cm with an average length of 14.43±2.39 cm. Fish weight ranged from 14.50-155.30 g with an average weight of 51.33±25.83 g. The growth pattern is negative allometric. The relative weight shows a value of 102.63±21.40, meaning that the source of feed is abundant in the Trichopodus trichopterus environment and the condition is healthy. The Fulcon condition factor value is 1.61±0.55 and the relative condition factor is 1.04±0.33, meaning that the condition factor value is below 3. This shows the cheek-shaped fish.Keywords: length weight; condition factor; Trichogaster pectoralis

BIODIVERSITY OF FISH FAMILY OSPHRONEMIDAE IN SWAMP WATERS IN BAGAN BILAH VILLAGE, DISTRICT OF PANAI TENGAH LABUHANBATU REGENCY

One of the swamp waters is located in Bagan Bilah Village, Panai Tengah District, Labuhanbatu Regency, North Sumatra Province. These swamp waters store a lot of fish diversity that has been used by the surrounding community. Among them are fish from the Osphronemidae family. This study aims to determine the biodiversity of fish of the Osphronemidae family in the swamp waters of Bagan Bilah Village. Fish sampling was carried out for 3 months, starting from October to December 2021. Fish are caught using traditional fishing gear called tangkol. The caught fish are collected, counted in number and then identified by species. The research data is calculated for its ecological index using the 2010 version of the Microsoft Excel application, then the data is displayed in tabular form. Based on the results of this study obtained 5 species of fish family Osphronemidae (Belontia hasselti, Betta imbellis, Trichogaster trichopterus, Trichopodus pectoralis, and Trichopsis vittatus). The Diversity Index (H') of Station 1 (0.78), Station 2 (0.76), and Station 3 (1.26). Uniformity Index (E) for Station 1 (0.43), Station 2 (0.42), and Station 3 (0.70). Dominance Index (C) for Station 1 (0.13), Station 2 (0.16), and Station 3 (0.28).

Co-infection of Candidatus Piscichlamydia Trichopodus (Order Chlamydiales) and Henneguya sp. (Myxosporea, Myxobolidae) in Snakeskin Gourami Trichopodus pectoralis (Regan 1910).

The present study describes a simultaneous infection of a novel Chlamydia-like organism (CLO) with a Myxozoa parasite, Henneguya sp. in snakeskin gourami Trichopodus pectoralis in Thailand. A new CLO is proposed “Candidatus Piscichlamydia trichopodus” (CPT) based on 16S rRNA phylogenetic analysis. Systemic intracellular CPT infection was confirmed by histological examination, in situ hybridization, PCR assay, and sequencing of 16S rRNA. This novel pathogen belongs to the order Chlamydiales but differs in certain aspects from other species. The histopathological changes associated with CPT infection were different from the typical pathological lesions of epitheliocystis caused by previously known CLO. Unlike other CLO, CPT localized in the connective tissue rather than in the epithelial cells and formed smaller clumps of intracellular bacteria that stained dark blue with hematoxylin. On the other hand, typical myxospores of the genus Henneguya with tails were observed in the gill sections. Infection with Henneguya sp. resulted in extensive destruction of the gill filaments, most likely leading to respiratory distress. Due to the frequency of co-infections and the unavailability of culture methods for CLO and Henneguya sp., it was difficult to determine which pathogens were directly responsible for the associated mortality. However, co-infections may increase the negative impact on the host and the severity of the disease. Given the commercial importance of the snakeskin gourami and its significant aquaculture potential, the findings of this study are important for further studies on disease prevention.

Improving the Quality of Frozen Fillets of Semi-Dried Gourami Fish (Trichogaster pectoralis) by Using Sorbitol and Citric Acid.

Semi-dried gourami fish (Trichogaster pectoralis) is popularly consumed domestically and exported as a frozen product. This study was conducted to prevent deterioration quality in frozen fish fillets during storage. This research aims to investigate the effects of sorbitol and citric acid at concentrations of 2.5% and 5% (w/w) of frozen gourami fish fillets compared to the fillets soaked in distilled water on physicochemical properties, such as cooking loss, cooking yield, drip loss, pH, TBARS, color, and texture profile analyses (TPA) during storage at −18 ± 2 °C for a period of 0, 20, and 40 days. The fish soaked in sorbitol and citric acid solutions had significantly (p < 0.05) higher protein and fat contents than the control sample. Sorbitol was able to retain moisture in the product; therefore, the drip loss and cooking loss were the lowest, and cooking yield was the highest among other samples (p < 0.05). The addition of 5% (w/v) citric acid in frozen fish fillets can significantly retard the thiobarbituric acid reactive substance (TBARS) (p < 0.05) during storage when compared to fish soaked in sorbitol solution kept for the same period. However, the addition of citric acid resulted in low quality in texture and color of frozen fish fillets. The use of sorbitol was the best alternative in frozen fish fillet product due to reducing the negative effects of freezing quality of the products and generating a cryoprotective effect compared to the fillets soaked in distilled water.

Isolation and selection of bacteria inhibiting Streptococcus agalactiae causing dark-body disease on snakeskin gourami fish (Trichogaster pectoralis)

Streptococcus agalactiae is one of the microbial pathogens causing the dark-body disease on snakeskin gourami fish (Trichogaster pectoralis) that affects the growth and quality of fish. This research aimed to isolate and select bacteria inhibiting S. agalactiae which are able to use for controling pathogenic bacteria instead of antibiotics. Fourteen bacteria strains were isolated and screened from healthy fishes, sediment and water samples at fish ponds in Dong Thap province. Among these strains, L7 strain showed the highest inhibition ability with the clear zone diameter was 9,3 mm. The results of the 16S rRNA sequence analysis indicated that the L7 strain belonged to Bacillus subtilis. The experiment to evaluate the inhibition capacity and fish disease control of selected B. subtilis in experimental conditions was conducted by challenging fish with S. agalactiae. Fishes in the control treatment was infected with S. agalactiae at 106 CFU/mL had survival rate 41,7%. The experimental treatments NT1, NT2, NT3 which were treated with B. subtilis at concentrations of 105 CFU/mL, 106 CFU/mL, and 107 CFU/mL gave higher survival rates compared with the non-treated control, with the rates of 60%, 76,7%, and 81,7%, respectively. These results revealed that the isolated B. subtilis is potential used in control dark-body disease on snakeskin gourami fish.

Sepat Siam fish community (Trichopodus pectoralis Regan, 1910) in Semayang Lake, East Kalimantan

Siam sepat (Trichopodus pectoralis) is a fish that lives with the characteristics of its life in mainland public waters such as rivers, lakes and flooded swamps. The Siam sepat is classified as a consumption fish, has morphological characteristics with a small mouth with a pointed snout and a flat body shape. The research was conducted from March to October 2018 in Semayang Lake, East Kalimantan. Fish samples obtained from fishermen’s catch using fishing gear, including nets, nets, tangkul, scoops and traps. This study used an enumerator to record the length and weight of the fish. The results of the research analysis showed that the size of the individuals who dominate the Siam sepat fish population is at the size of 14.0-17.0 cm (60.8%), the allometric growth pattern (-) with the equation W = 0.0393 * L2.6409. The size of the first caught (Lc) of the Siam Sepat fish was 17.31 cm, the maximum average length (L∞) was 22.75 cm and the growth coefficient (K) was 0.78 per year. Natural mortality (M) and fishing mortality (F) were 1.64 and 2.64 per year, respectively. Thus the rate of exploitation (E) = 0.62 has exceeded the optimum value indicating that the fishing effort of Siamese septic fish in Lake Semayang has occurred overfishing.