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The paradise threadfin, Polynemus paradiseus is one of the commercially important brackishwater finfish of the family Perciformes in Bangladesh. The present study aimed to investigate the reproductive biology of paradise threadfin from Shibsa River in Bangladesh. The fish samples (66) were collected from May 2021 to April 2022. The relationship between body weight (BW) and total length (TL) of sampled fish were analyzed with a non-linear power equation where R2 = 0.915 and ‘b’ value (3.22) indicates a positive allometric growth pattern. Linear relationship indicates gonad weight (GW) increases with the BW and fecundity increases with BW, TL, GW and gonadosomatic index (GSI). The highest GSI was recorded in June (11.10±0.91), whereas, the lowest in November (0.44±0.08). The maximum fecundity was found in June (32410±7790). Ovarian histology displayed different stages of oocyte development. Late yolk granule stage (LYGS) was found in the months of September-October and May-July, respectively. Based on the GSI, fecundity and ovarian histology, it was revealed that the spawning season of P. paradiseus was from May to October with a major peak in June and minor one in September. The knowledge on different aspects of reproductive biology of paradise threadfin would be helpful for planning captive breeding and to design sustainable management policies for conservation of this species in the south-west coast of Bangladesh.

Climate change and sea-level rise cause seawater intrusion into freshwater ecosystems, risking increased salinity exposure for freshwater fish, endangering their long-term sustenance. To understand the effects of environmentally realistic increase in salinity exposure on freshwater fish, a total of 120 banded gourami, Trichogaster fasciata ( 8.54 g average initial weight) were exposed to four different salinities (0, 3, 6, and 9‰) for 90 days. The weight gain and specific growth rate values were significantly higher in the fish exposed to 3‰ compared to 0‰, and the lowest feed conversion ratio and survival rate were recorded in 3‰ and 9‰, respectively. The blood glucose and hemoglobin contents were found to be significantly higher and lower at 9‰ after 30 and 60 days, respectively, relative to 0‰. Moreover, significant low red blood cell counts were found at 6 and 9‰ after 30 and 90 days, respectively. Whereas, the white blood cell counts showed an opposite trend. Abnormalities of erythrocyte shape were significantly higher at 9‰, compared to 0‰. Results suggest that long-term exposure to high salinity (6, and 9‰) would cause osmotic stress and impair the physiological performance of freshwater gourami. [ABSTRACT FROM AUTHOR]

The present study was conducted to understand the changes in gonads and hematological parameters in climbing perch (Anabas testudineus) exposed to synthetic estrogen and progestogen [mixture of ethinylestradiol (EE2) and desogestrel (DES)]. Climbing perch were exposed to four different concentrations of EE2/DES mixtures, viz. 0 ng of EE2 and DES/L (T0), 3 ng EE2 and 15 ng DES/L (T3), 30 ng EE2 and 150 ng DES/L (T30), and 300 ng EE2 and 1500 ng DES/L (T300) for 60 days. On days 45 and 60, samples were taken to assess changes in somatic indexes, gonad histology, and hematological parameters. The gonadosomatic index (GSI) increased in both females and males with increasing concentrations of estrogen mixtures except for T30 females, which was the lowest among all\four treatments. The hepatosomatic index (HSI) was observed to be increased in males as estrogen content increased. However, compared to fish at T0, HSI in female individuals did not vary in T30 fish, where the value was the highest among all the treatments. On day 45, histological observations showed no feminization or intersexuality but several germ-cell deformities in the ovary (adhesion, degenerated oocyte wall, degenerated granulose layer, increased interfollicular space, atretic follicle, and cytoplasmic clumping) and testes (increased interstitial area, focal loss of spermatocyte, dilation of the lumen, breakage of tubular epithelium, and elongated seminiferous tubule) were observed in fish exposed to EE2 and DES. Fish reared at T30 had lower RBC count, hemoglobin (Hb), glucose, and hematocrit levels. On day 60, fish reared at T30 had the highest Hb content compared to fish raised in other treatment conditions. WBC was progressively higher with increasing EE2/DES concentrations. Significant erythrocyte cytoplasmic abnormalities and erythrocyte nuclear abnormalities were observed in fish exposed to higher EE2/DES concentrations. The present study provides insights into the adverse impacts of synthetic estrogens sourced from human contraceptive pills on fish physiology. [ABSTRACT FROM AUTHOR]

Thiamethoxam is a broad-spectrum pesticide used in Bangladesh to protect crops from pests. In several ways, this pesticide ends up in aquatic ecosystems. Researchers have detected its existence in waterbodies. However, the harmful effects on non-target aquatic residents are not well studied and reported. As a result, the study sought to investigate the effect of thiamethoxam on the liver and kidney tissues of banded gourami (Trichogaster fasciata) using histopathological observations. Fish were exposed to five sub-lethal concentrations (in triplicates) of thiamethoxam (9.37, 18.75, 37.5, 75, and 150 mg/L) and 0 mg/L (control) for 90 days. Fish livers and kidneys were sampled on days 30, 60, and 90 of thiamethoxam exposure. The histopathological changes observed in thiamethoxam exposed fish were autolysis, acute cellular swelling, vacuolation, necrosis, and fatty change in the liver, whereas irregular renal corpuscle and cellular degradation of tissue were also observed in the kidney. The present study reveals that thiamethoxam can affect the livers and kidneys of Banded Gourami; therefore, the usage of this insecticide in agriculture should be applied carefully and monitored to avoid entry into water bodies. [ABSTRACT FROM AUTHOR]

The early B cell protein γ5 is an essential component of the surrogate light chain and the preB cell receptor (preBCR), which is critical for optimal B cell development. To investigate the effect of l5 and/or B cells on bone acquisition over time, we developed a panel of JH-/-, l5-/-, JH-/- l5-/-, and wild-type (WT) BALB/c mice and then studied postnatal bone development and aging in these mice at one, six, twelve, and twenty-two months of age. The trabecular bone volume over total volume (BV/TV) in JH-/- mice was similar to WT mice at all ages. In contrast, at six months of age and thereafter, l5-/- and JH -/-l5-/- micedemonstrated a severe decrease in trabecular bone mass. Surprisingly, bone mass in six-month-old l5-/- and JH-/-l5-/- mice was similar to or even lower than in aged (twenty-two-months) WT mice, suggesting accelerated skeletal aging. The postnatal development and the acquisition of cortical bone mass in JH-/-l5-/- mice were generally comparable to WT. However, JH-/-l5-/- mice showed a significant decrease in cortical BV/TV at six- and twelve months of age. To examine the contribution of l5 and B cells to postnatal bone synthesis, we separately transplanted whole bone marrow cells from JH -/-l5-/- and WTmice into irradiated JH-/-l5-/- and WT recipients. WT recipients of JH -/-l5-/-marrow cells failed to show acquisition of trabecular bone mass, whereas transplanting WT marrow cells into JH-/-l5-/- recipients led to the recovery of trabecular bone mass. Transfer of WT marrow cells into JH-/-l5-/- micepromoted synthesis of new cortical and trabecular bone. Our findings indicate that l5 plays a major role in preserving bone mass during postnatal development and skeletal aging which is distinct from its role in B cell development. The absence of both l5 and B cells in JH-/-l5-/- mice leads to delayed acquisition of cortical bone during postnatal development. Dissecting the mechanism(s) by which l5 regulates bone homeostasis may provide new avenues for the treatment of age-related loss of bone mass and osteoporosis. [ABSTRACT FROM AUTHOR]