International Journal of Aquatic Biology
Volume:8 Issue: 6, Dec 2020

The gagora catfish, Arius gagora is a species of Ariidae family normally exist in estuaries and tidal rivers of Bangladesh and India. In the present study, the reproductive biology of A. gagora was assessed in Meghna River system at Kushiara River. Length-weight relationship was found strongly correlated for male (r2 = 0.98), female (r2 = 0.97) and combined sex (r2 = 0.81), respectively. Chi-square tests revealed no significant difference between sex ratios round the year and not deviated from the expected value of 1:1 (χ2 = 5.57) and the critical chi-square value calculated was 143.25. The fecundity found to be ranged from 43333.12±829.83 to 53948.81±1743.28 in April to August. The relationship of fecundity with ovary weight (r2 = 0.79), ovary length (r2 = 0.88), total length (r2 = 0.85) and total weight (r2 = 0.68) were found positively correlated. Monthly study of gonadosomatic index (GSI) revealed that the breeding season for this fish species may be between July to August with a single peak spawning month in August. Size at sexual maturity was estimated as 30.01 cm total length. Fulton’s condition factor (K) value varied in both males and females and indicates that the overall health condition of both the male and female were excellent. Breeding season was found significantly correlated with rainfall, but not with other biological, meteorological, and hydrological parameters. Ovarian development of A. gagora was assessed macroscopically and three broad gonad developmental stages were identified. Maturity was specified based on the presence of green egg in the peritoneal cavity. These findings should benefit and improve the sustainable management and conservation of this species both in Bangladesh and its bordering countries.

The aim of this study was to isolate and identify Lactobacillus with probiotic potential from gastrointestinal tracts (GIT) of Capoeta razii and bighead carp, Aristichthys nobilis. GIT samples of fifteen bighead carp and sixteen C. razii were collected and homogenized in 0.9% NaCl buffer and cultured on MRS medium. Nine isolates were obtained from C. razii and 18 insolates from bighead carp. The isolates were sequentially subjected to acid- and bile salt-resistance test. Three isolates from C. razii and one isolate from bighead carp were both acid- and bile salt-resistant. These isolates were identified by sequencing 16s rRNA and subjected to BLAST analysis to find the highest similarity in GeneBank. The isolate from bighead carp and two isolates from C. razii were L. plantarum with the highest similarity with strain DR7. One of the isolates from C. razii was L. brevis with the highest similarity with strains 100D8 and BDGP6. Further studies are encouraged to assess these probiotic effects in aquaculture species growth performance and health status.

Fish and fisheries have long been subject of art works of ancient Persians, Egyptians and Chinese. Art has a variety of dimensions and perspectives associated with nature/environment including marine or freshwater bodies. Following the idea of linking art, fish and fisheries and the marine environment, in this study, we used local set-net fishing known as Moshta as a traditional fishing gear at the coastal area of Bandar Abbas, Iran to present emotional state and concept of repeatability. The Moshta fishing (i) repeats almost every day, (ii) stimulates emotions, (iii) brings deaths to fishes, (iv) supplies food to peoples and birds, and (v) contributes to the economy of local families. Hence, there is always a reproducibility creation in this man-made fishing gear. This process in a worthy way to bring lights to the creation of different links between fish and fisheries from one hand and art in the other hand.

Pre-spawning reproductive behavior on the mudflat surface was reported previously for the mudskipper, Periophthalmus modestus, but it remains unknown how a pair spawns and fertilizes eggs within the spawning chamber of a burrow. In this study, we recorded reproductive behaviors from burrow entry of a pair to the departure of a female. In those cases, where spawning was suspected from a drastic reduction in the distension of the female’s belly (N = 4), the female remained inside a burrow for 240-350 min without coming out onto the mudflat surface. In contrast, the male often but irregularly emerged from the burrow. In one case, a second male entered a burrow 169 min after the burrow entry of a female, resulting in her desertion from the burrow without spawning. During burrow cohabitation of the pair, burrow openings were often clogged by mud from inside. After the female left the burrow, the male remained inside the burrow for variable periods. Then, the male guarded the burrow for about one week. Upon termination of the burrow guarding, the male began excavating a new burrow near the previous one or repaired the burrow that he had guarded. A hypothesized scenario is proposed for the reproduction of this species for further investigation.

Thuridilla indopacifica Gosliner, 1995 (Sacoglossa, Plakobranchidae) is a rare species in the Sacoglossan nudibranch that only reported from the South Africa and Western Australia. This study records T. indopacifica from the Gulf of Oman for the first time showing its expansion to the northwest of Indian Ocean.

This study documents microplastics (MPs) in the top three commercially sold fishes viz. Auxis rochei, Rastrelliger kanagurta and Chanos chanos in major public markets of Cebu Island, Philippines. MPs were found in the gastrointestinal tracts (FGIT) and quantified and characterized according to size, type, and color. In general, nine (97.3%) of 81 FGIT samples contained 635 total pieces of MPs with size ranging 0.01 to 0.50 and 1.00 to 2.00 mm. Transparent microfibers (91%) were the most predominant MPs, with blue (48%) as the most common MP color observed, followed by red (39%), black (8%) and white (5%). Chanos chanos proved to be the most susceptible fish to MP ingestion with a mean average of 11.6 pieces per individual fish, followed by A. rochei with 6.6 pieces, and R. kanagurta with 5.3 pieces. The results indicated that MPs were ubiquitous and high in commercially sold fishes in major public wet markets of Cebu Island, Philippines. The ingestion of fishes is of primary concern as a route of human exposure to MPs because they filter a large volume of seawater and are typically eaten whole without gut removal. Further study is needed on the potential consequences of MPs to aquatic populations to assess comprehensive exposure integrating multiple sources and routes.

The present study used the Ecological State Macrophyte Index (ESMI) and the multivariate statistical methods to assess the ecological status and the variation of macrophytes in a tropical wetland system. Six sites were selected from rehabilitated and non-rehabilitated areas of an urban tropical wetland and the water quality parameters (water pH, temperature, conductivity, total dissolved solids (TDS), dissolved oxygen (DO), visibility, biological oxygen demand 5 days after incubation (BOD5), chemical oxygen demand (COD), nitrate, chlorophyll-a and total phosphorus concentrations), sediment quality parameters (pH, organic matter content, percentage sand, silt and clay content) and abundance of aquatic macrophytes were measured. Shannon Weiner diversity index, percentage vegetation under anthropo-pressure, macrophyte settlement rate and ESMI were calculated. Significant variations in the water and sediment quality parameters were observed and ten species of aquatic macrophytes were recorded. Salvinia melosta and Cypreus iria were recorded only from the non-rehabilitated sites. Although there was no significant difference in the percentage anthropo-pressure among study sites, the rehabilitated sites were displayed low anthropo-pressure. The sites in the non-rehabilitated area showed a significantly lower macrophyte settlement rate. ESMI and macrophyte abundance showed significant correlations with water quality parameters. Based on the results, it can be recommended that applications based on ESMI and multivariate statistics can be used to assess the ecological status of tropical wetlands.

Nanoparticles are widely used in removing bacteria from water and sewage. This study evaluated the effect of graphene/silver nanocomposite on the removal of coliform from a dairy effluent. The composition was synthesized and its properties were determined using different techniques such as SEM, XRD and FTIR. The effects of various factors, including pH, adsorbent dose and contact time on coliform removal from solution were studied. Antimicrobial activity of the nanocomposite was examined by pour plate method in a VRBL medium. After preparing the VRBL medium from the sewage effluent, 1 mL of nanocomposite solution and 1 mL of bacterial suspension containing 9×104 CFU/mL were added into each of the plates. According to the results, the rate of silver ion release is faster as pH decreases, which naturally results in the increase of disinfection. Moreover, a higher percentage of removal occurred with an increase in contact time and nanocomposite dose due to higher exposure to nanoparticles and their higher penetration into bacterial cell membrane. Therefore, nanoparticles produced by this method exhibited good antibacterial activity, so that 100% of bacteria were eliminated at a nanocomposite concentration of 3.4 g/L and pH=5, after 90 min.