Fecundity and Gonadosomatic Index of Sucker Throat Catfish, Pseudecheneis sulcata (McClelland, 1842) from the Snow-fed Tamor River in Eastern Nepal

In comparison to other nations, the Nepalese information on the reproductive biology of hill-stream fish is limited. So, the purpose of the present study was to provide information related to reproductive biology of a hill-stream sucker throat catfish Pseudecheneis sulcata from the snow-fed Tamor River, Nepal. The study was carried out from June 2018 to May 2019. A total of 57 female fish was collected. The fecundity of 22 females was assessed, while the gonadosomatic index was determined using all the collected samples. The absolute fecundity ranged from 2,316 to 7,597 eggs, with an average of 3,660 ± 210. This range of absolute fecundity indicates that Pseudecheneis sulcata is a moderately fecund fish when compared to certain low fecund species and some exceptionally fecund fish with tens of thousands of eggs. Relative fecundity ranged from 65.47 to 129.11 with a mean of 88.98 ± 4.35. The present study demonstrated that absolute fecundity was moderately correlated with total length (r = 0.45) and strongly linked with body weight (r = 0.78), and ovary weight (r = 0.80). Mean gonadosomatic index (GSI) was recorded the highest in January (15.7 ± 1.22%), and showed a decrease in the subsequent month of February (10.3 ± 0.75%), March (6.25 ± 0.28%) and April (1.66 ± 0.40%). The trends of GSI might have indicated that the sucker throat catfish was a batch spawner, with spawning season occuring between January and March.

Community of macroparasites of the Pacific barracuda Sphyraena ensis Jordan and Gilbert, 1882 (Perciformes, Sphyraenidae) from the north coast of Peru

This study aimed to report the community of macroparasites of the Pacific barracuda Sphyraena ensis Jordan and Gilbert, 1882 (Perciformes, Sphyraenidae) from the north coast of Peru. From September to October 2019, 138 specimens of S. ensis were acquired from Caleta de Zorritos, Contralmirante Villar Province, Tumbes, on the north coast of Peru. The community of parasites found consisted of nine species of parasites including monogeneans, copepods, trematodes and nematodes. The total body length of the fish was negatively correlated with the mean intensity of infestation of Pseudochauhanea sp. The mean abundance of Pseudochauhanea sp. also showed a marked significant difference between the populations of male and female fish, being more associated with males. We provide a list of macroparasites recorded in fish of the genus Sphyraena in the Eastern Pacific Ocean. Checklist dataset published through GBIF (Doi: 10.15470/5htffh)

Keeping Lagocephalus sceleratus off the Table: Sources of Variation in the Quantity of TTX, TTX Analogues, and Risk of Tetrodotoxication

The invasion of the tetrodotoxin (TTX)-bearing silver-cheeked toadfish and potential poisoning due to its consumption (tetrodotoxication) threatens public safety in the Mediterranean Sea. In this study, TTX and TTX analogues of Lagocephalus sceleratus (Gmelin, 1789) were measured using liquid chromatography tandem mass spectrometry (LC-MS/MS) in fish collected off the island of Crete (Southern Mediterranean). We tested the synergistic effect of a suite of factors potentially affecting toxins’ levels and tetrodotoxication risk using general and generalized linear models, respectively. The type of tissue, geographic origin (Cretan Sea, Libyan Sea), sex, and fish maturity stage were significant predictors of toxin concentrations. Mean TTX was higher in gonads and lower in muscles, higher in the Libyan Sea and in female fish, and lower in juvenile (virgin) fish. The concentration of TTX was also significantly and positively correlated with the concentration of several TTX analogues (4-epiTTX, 4,9-anhydroTTX, 11-deoxyTTX, 5,11/6,11-dideoxyTTX, 5,6,11-trideoxyTTX, 11-norTTX-6-ol). The analysis showed that fish originating from the Libyan Sea had significantly higher probability to cause tetrodotoxication in case of consumption. The variability explained by the models developed in this study was relatively low, indicating that toxin levels are hard to predict and the consumption of L. sceleratus should therefore be avoided.

Community of macroparasites of the Pacific barracuda Sphyraena ensis Jordan and Gilbert, 1882 (Perciformes, Sphyraenidae) from the north coast of Peru

This study aimed to report the community of macroparasites of the Pacific barracuda Sphyraena ensis Jordan and Gilbert, 1882 (Perciformes, Sphyraenidae) from the north coast of Peru. From September to October 2019, 138 specimens of S. ensis were acquired from Caleta de Zorritos, Contralmirante Villar Province, Tumbes, on the north coast of Peru. The community of parasites found consisted of nine species of parasites including monogeneans, copepods, trematodes and nematodes. The total body length of the fish was negatively correlated with the mean intensity of infestation of Pseudochauhanea sp. The mean abundance of Pseudochauhanea sp. also showed a marked significant difference between the populations of male and female fish, being more associated with males. We provide a list of macroparasites recorded in fish of the genus Sphyraena in the Eastern Pacific Ocean. Checklist dataset published through GBIF (Doi: 10.15470/5htffh)

Mackerel (Scomber australasicus) Reproduction in Northeastern Taiwan

Blue mackerel (Scomber australasicus) is a crucial target species for coastal fisheries in Taiwan, and additionally it has maintained its status as the highest-produced species. The timely measurement of spawning status is crucial for determining the correct management strategy for this species. The objective of this study was to determine size at maturity, fecundity, batch fecundity, and spawning frequency on the basis of samples collected from Nan-Fang-Ao fishing port in Yilan, during the spawning season from 2017 to 2019. Histological sections indicated that the blue mackerel were multiple spawners; a higher percentage of female fish spawned at the peak of the gonadosomatic index. The 50% sizes at maturity were 32.02, 32.13, and 29.64 cm. Mean total fecundity (batch fecundity) was 165 (103), 229 (96), and 210 (68) oocytes per ovary-free weight (g) for 2017, 2018, and 2019, respectively; fecundity was determined through observation of postovulatory follicles (POFs). The spawning frequencies (spawning fraction) in 2017, 2018, and 2019 were 3–10 days (0.13), 4–14 days (0.08), and 4–12 days (0.09), respectively. The spawning frequencies determined through the three estimated methods, namely the sums of (a) hydrated and Day 0 POFs; (b) Day 1+ POFs, and (c) all data combined, were 1 spawning event per 8, 10, and 9 days, respectively. The reproduction of the blue mackerel was greater in 2017 than it was in 2018 or 2019, as indicated by the higher batch fecundity and shorter spawning seasons. Environmental factors should also be considered as a major factor influencing successful reproduction and spawning season

Power Play of Commensal Bacteria in the Buccal Cavity of Female Nile Tilapia

Fish are widely exposed to higher microbial loads compared to land and air animals. It is known that the microbiome plays an essential role in the health and development of the host. The oral microbiome is vital in females of different organisms, including the maternal mouthbrooding species such as Nile tilapia (Oreochromis niloticus). The present study reports for the first time the microbial composition in the buccal cavity of female and male Nile tilapia reared in a recirculating aquaculture system. Mucus samples were collected from the buccal cavity of 58 adult fish (∼1 kg), and 16S rRNA gene amplicon sequencing was used to profile the microbial communities in females and males. The analysis revealed that opportunistic pathogens such as Streptococcus sp. were less abundant in the female buccal cavity. The power play of certain bacteria such as Acinetobacter, Acidobacteria (GP4 and GP6), and Saccharibacteria that have known metabolic advantages was evident in females compared to males. Association networks inferred from relative abundances showed few microbe–microbe interactions of opportunistic pathogens in female fish. The findings of opportunistic bacteria and their interactions with other microbes will be valuable for improving Nile tilapia rearing practices. The presence of bacteria with specific functions in the buccal cavity of female fish points to their ability to create a protective microbial ecosystem for the offspring.

Observation on the reproductive behavior and embryo of the daisy’s ricefish, Oryzias woworae in laboratory condition

Oryzias woworae is an endemic ricefish from Muna Island, Southeast Sulawesi, traded as an ornamental fish. Information on the biology of these fish is very lacking, including their reproductive. These fish also face the threat of population decreasing in the wild. The research aimed to examine the spawning behavior and embryonic of O. woworae as the basis for aquaculture. Fish spawning was carried out using 1 male: 1 female ratio, which was repeated three times. The observed spawning behavior was pre-spawning, mating process, egg number, and morphology. Behavioral observations were carried out for five days of spawning. Observation of embryos was carried out to see the stages of embryo development until hatching. The results obtained on pre-spawning behavior were changes in body color and blackened fins in males, which did not occur in female fish. Males actively swim by approaching their dorsal and anal fins while chasing females. The female releases the eggs and is attached to the substrate, rapidly fertilized by the male fish. There is a phenomenon of females carrying eggs on the genital pore before being released to the substrate (non-pelvic brooder). Spawning only occurs during the day, and spawning is getting faster, which is at 09:00 AM on the fifth day. Oryzias woworae eggs have a diameter of 1.3 ± 0.2 mm, equipped with attaching and non-attaching filaments. Observations of O. woworae embryos showed that embryo hatching occurred at seven days 23 hours post-fertilization.

Masculinization of betta fish (Betta sp) using cow testic flour through Artemia Immersion

Betta fish (Betta sp) is a freshwater ornamental fish during the pandemic that is very popular with the public. However, people tend to prefer male betta fish than female fish. To deal with the large number of requests, a sex reversal technique is carried out which applies hormonal engineering to change female to male sexual characters (masculinization) using natural ingredients, namely cow testicle flour. The purpose of this study was to analyze the dose of bovine testicular flour hormone on the process of oral male betta fish larvae. This research was conducted in Moncongloe Village, Maros Regency, from July to September 2021. The production of beef testicle flour was carried out in the Chemical Engineering laboratory, Ujung Pandang State Polytechnic. Betta fish seeds were kept each in an aquarium measuring 20 cm x 14 cm x 20 cm as many as 12 pieces. Soaking artemia with beef testicle flour with a predetermined dose of 60 mg L-1, 80 mg L-1 and 100 mg L-1, the duration of immersion is 24 hours. This study used a one-factor completely randomized design (CRD). The results obtained were the highest percentage of male genitalia at a dose of 100 mg L-1 with a percentage of 66.7%. The survival rate of betta fish during the maintenance period with different doses of cow testicles obtained data ranging from 80-100%.

Short Communication: Investigating gonad length and fecundity in mudskippers (Gobiidae) at the Musi River estuary, South Sumatra, Indonesia

Ridho MR, Patriono E, Wati DR, Pratama R, Avesena M. 2021. Short Communication: Investigating gonad length and fecundity in mudskippers (Gobiidae) at the Musi River estuary, South Sumatra, Indonesia. Biodiversitas 22: 4413-4420. Information on the biological aspects of mudskipper (Gobiidae) reproduction is needed as a conservation effort to use economically valuable and sustainable resources in the future. This can be used to enrich the information on the status of the mudskipper research at the Musi River estuary, South Sumatra, Indonesia. The field sampling was carried out by using the purposive sampling method. The sampling of fish was carried out by the researchers and assisted by the people of the community using fishing rods and bubu fish traps. The results showed that 122 mudskipper were obtained, which consisted of four species Boleophthalmus boddarti, Boleophthalmus dussumieri, Periophthalmus chrysospilos, Periophthalmodon schlosseri. 93 male and 29 female fish were caught, the sex ratio was 3.20:1. There are more male than female fish overall with the sampling method used. Most of the female fish fecundity was reported in P. chrysospilos, namely 23,270-36,264 items in GM (III) and ranged from 40,825-87,749 items in GM (IV). The largest egg diameter was reported in P. chrysospilos by 0.051-0.069 mm (GML III) and 0.053-0.062 mm (GML IV), while the smallest weight and length were reported in P. chrysospilos than other species. The egg size was not positively correlated with body size.

Estimation of Fishing Mortality Rate and Exploitation Status of Yellowstrip Scad (Selaroides leptolepis) in Tomini Bay using Von Bertalanffy Growth Model Approach

Highlight ResearchThe fishing area of S. leptolepis in this study was confirmed to be located in Tomini BayThe fish samples were gathered randomly from fishers’ catch using purse seinesThe growth curve for the male and female fish data were both plotted following the trend of the Von Bertalanffy equationThis study estimates the growth parameters, mortality, and exploitation rates of the male and female fish separately.AbstractComprehensive data is required for implementing sustainable fisheries management. Population dynamic and stock assessment aspects of Selaroides leptolepis species in Tomini Bay have not been entirely reported. This study aimed to determine the fishing mortality rate and exploitation status of S. leptolepis in Tomini Bay by calculating Von Bertalanffy growth model parameters (L∞, K, t0) then plotting them into Pauly's empirical equation. The sampling was conducted monthly from April to September 2020 at Gorontalo City Fishing Port. Samples were collected randomly from five commercial fishing vessels shortly after the fishermen landed their catch at the fishing port. All fish samples were confirmed to be obtained by the fishermen from Tomini waters. The growth parameters of the samples were analyzed using FiSAT II based on Von Bertalanffy mathematical model. While the mortality and exploitation values were calculated manually using Pauly's equation. The study showed that the growth parameter values of S. leptolepis in Tomini Bay were 245.47 mm, 0.49/year, and -3.04/year for males, while 227.80 mm, 0.63/year, and -2.72/year for females separately for L∞, K, and t0. The total, natural, and fishing mortality rates were 3.06/year, 0.61/year, and 2.45/year for males and 0.99/year, 0.74/year, and 0.25/year for females. The analysis results showed that the female's natural mortality (M) was higher than the male. In contrast, the fishing mortality (F) and total mortality (Z) of male fish exceed the female. The exploitation value of males (E=0.80) was greater than that of females (E=0.26).