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When no reference genome exists for a species, prior estimation of genome size is essential to understand the genome content and the read depth in NGS (Swathi et al., 2018). Keywords: flow cytometry; genome; genome size; Mugil cephalus EN flow cytometry genome genome size Mugil cephalus 1151 1158 8 01/21/22 20220215 NES 220215 INTRODUCTION The striped grey mullet, I Mugil cephalus i , is the most widespread and economically important high-value species among the family Mugilidae (Order: Mugiliformes), which comprises a total of 26 valid genera and 79 valid species (Eschmeyer et al., 2021). Hence, before assigning a genome size value to this fish species, we have used several tissues and larval stages of fish to minimize the variations and to get an average estimate of the genome size. The approach to estimate genome size from different larval stages and tissues using flow cytometry was to eliminate variations arising due to endogenous or exogenous factors, which might influence the genome size estimate in an organism. [Extracted from the article]

Silver moony, Monodactylus argenteus (Linnaeus, 1758), belonging to the family Monodactylidae, has high significance in the ornamental fish industry. The present study provides the details of captive broodstock maturation, induced breeding and larval rearing of this species for the first time. Juveniles were collected from wild and raised to adults in net cages. Female with oocyte diameter =500 µm and oozing males were selected in the sex ratio of 1:2 (female: male) and induced to spawn using a single dose of LHRHa. Spontaneous spawning and fertilization were observed after 36 to 40 hr of hormonal induction. The average fertilization and hatching rates were 83.50 ± 4.37% and 70.83 ± 5.19% respectively. The incubation period was observed to be 18 to 20 hr at a temperature of 29 ± 1.8°C. Newly hatched larvae measured 1,630 ± 0.20 µm in length. Larval rearing was carried out in 500‐L circular fibre reinforced plastic tanks using a green water system. Larvae were stocked at 5 L−1 in larval rearing tanks. Initial mouth opening and complete yolk absorption were observed at 48 and 96 hr post‐hatching respectively. Larval feeding was done using live feeds, rotifer and Artemia nauplii. Metamorphosis began on 23 dph, and 100% larvae became juvenile on 32 dph with an average survival rate of 49.6 ± 8.73%. These findings on the development of captive seed production of silver moony would pave the way for mass scale production and reduced exploitation of wild stocks. [ABSTRACT FROM AUTHOR]

Viral nervous necrosis (VNN) affects more than 120 species mostly belonging to the order Perciformes. However, none of the brackishwater species belonging to the family Cichlidae under the order Perciformes are reported to be susceptible. Hence, the present experiment was undertaken to study the susceptibility of the brackishwater cichlid, pearlspot, Etroplus suratensis to NNV. Thirty‐day‐old pearlspot larvae were infected with NNV by immersion. Mortality was recorded till 14 days post‐infection, and the infected larvae were subjected to nested RT‐PCR and histology. The virus was isolated from infected larvae using SSN‐1 cells. To study the replication of the virus in vitro, primary cultured brain cells of E. suratensis and IEK cells were infected with NNV. No mortality was observed in any of the control or experimentally infected larvae. However, the experimentally infected larvae were positive for NNV by nested RT‐PCR and the virus was isolated using SSN‐1 cells. Further, the infected pearlspot brain cells and IEK cells showed cytopathic effect at second and third passage of the virus and they were positive for NNV by nested RT‐PCR. Pearlspot is relatively resistant to VNN although the virus could replicate in the larvae and in cell culture. [ABSTRACT FROM AUTHOR]

Abstract: Mystus gulio, the long whiskers catfish, is a popular food fish and potential candidate species for aquaculture in Sundarban area of India and Bangladesh. Recently, catch of this species has declined due to overfishing and various ecological changes. In the present study, mature fish was induced to spawn in captivity through intramuscular injection of human chorionic gonadotropin at the doses of 10 IU/g to female and 5 IU/g to male. Photomicrographs of all developmental stages of live embryo and larvae were documented with the aid of a light microscope. Results demonstrated that morula, blastula, gastrula and neurula and organogenesis ended at 1:30‐, 3:00‐, 5:30‐, 7:30‐ and 17:15‐hour post‐spawning (hps) respectively. Heartbeat and muscular contraction of embryo commenced at 8:30 and 11.15 hps respectively. Hatching of embryo started after an incubation period of 17:30 hour at an ambient temperature of 29 ± 1°C. The newly hatched larvae measured 2.17 ± 0.29 mm in total length with a yolk volume of 0.165 ± 0.03 mm3 started feeding 36 hr after hatching. The present study, on induced breeding and chronological development of M. gulio embryo, will have significant implications on conservation and seed production for aquaculture. [ABSTRACT FROM AUTHOR]

Soil and water interactions and their influence on growth and production in different densities ( SD8 & SD16) under zero water exchange were studied in two successive crops of Penaeus monodon in Tamil Nadu, India during 2007 and 2008. Scraping and tilling during pond preparation increased the mineralization rate than scraping only. During crop, there was no significant difference in soil organic carbon and total nitrogen between the SDs. However, as the crop progressed, organic carbon and total nitrogen content of the soil showed significant difference under both the SDs. Between the SDs, nitrate and phosphate content in water significantly differed, whereas the progress of the crop significantly increased both available and total nutrients. Mass balance of nitrogen indicated that applied feed contributed to 97.4-98.5% of input nitrogen, of which nitrogen in sediment accounted for 16.5-27.3%, nitrogen recovery in shrimp was 34.2-43.6% and the nitrogen lost through denitrification and volatilization varied from 4.7% to 34.7%. Zero water exchange system is highly efficient as nitrogen recovery is higher in shrimp and lower in discharge water. Lack of significant difference in metabolites between the SDs indicates the role of aeration and probiotics in sustaining SD16 cultures. [ABSTRACT FROM AUTHOR]

With the objective to develop an indoor tank seed rearing system for pearlspot ( Etroplus suratensis), effects of three stocking densities in presence or absence of soil base were evaluated on growth, weight variation, survival and body composition in a 60-day trial. The experiment had a 3 × 2 factorial design with three levels of stocking density (150, 300 and 450 fish m−3) and two levels of soil base (with and without) in triplicates. Pearlspot fry (27.5 ± 0.5 mm/0.39 ± 0.02 g) were stocked in experimental tanks (Length×Breadth×Height: 0.65 × 0.50 × 0.48 m) and fed with a formulated diet containing 29.85% crude protein. Increasing the stocking density from 150 to 450 fish m−3 significantly decreased the growth (average body weight and total length), daily weight gain, specific growth rate and survival ( P < 0.001) and increased the feed conversion ratio ( P < 0.01). Significantly lower growth and survival were observed in treatment having soil base compared with that of without soil base ( P < 0.001). However, coefficients of variation at harvest weight and body composition of fingerlings were independent to stocking density and presence or absence of soil base ( P > 0.05). A significant positive interaction effect of stocking density and presence or absence of soil base was observed on average body weight ( P < 0.05) and survival ( P < 0.001) of pearlspot fingerlings. This study suggests that stocking density of 150 fish m−3 without soil base in tanks would be appropriate for raising pearlspot fingerlings in brackishwater indoor seed rearing system. [ABSTRACT FROM AUTHOR]