The purpose of this study is to compare the effects of probiotics, prebiotics, and their synergism against antibiotics on the growth performance and hematology of Nile tilapia (Oreochromis niloticus). The study was designed by using five treatments over 75 days in which T_Con (control), T_Ant (antibiotics: Cotrim vet), T_Pro (commercial probiotics: pond care), T_Pre (prebiotics: spirulina), and T_Syn (synbiotic: probiotic and prebiotic) were used. All the treatments showed significant ( < 0.05) improvements in growth and feed utilization parameters. The highest mean final growth was found in T_Syn (13.79 ± 0.11) and then in T_Pre (13.61 ± 0.02), T_Pro (13.22 ± 0.12), T_Ant (10.04 ± 0.7), and T_Con (8.89 ± 0.19). Weight gain and specific growth rate were significantly ( < 0.05) different between treatments. The food conversion ratio varied significantly ( < 0.05) across treatments and the lowest value was observed in T_Pro (1.13 ± 0.021). The protein efficiency ratio (PER) was significantly ( < 0.05) different between treatments and the highest value was in T_Pro (3.1 ± 0.05). The survival rate was not significantly ( < 0.05) different between treatments. The highest white blood cell (WBC) counts were found in T_Syn (12.63 ± 0.11) followed by T_Pre (12.6 ± 0.2), T_Pro (12.32 ± 0.12), T_Con (12.16 ± 0.105), and T_Ant (11.03 ± 0.46). The values of red blood cells and platelets were not statistically significant ( < 0.05) among the different treatments. However, all treatments showed normal hepatocyte structure in liver tissue histology, and intense hepatic lipid vacuoles in T_Syn indicated improved growth. The higher growth performance and feed utilization values were observed in probiotics, prebiotics, and their synergism units compared to antibiotic treatment. Therefore, probiotics, prebiotics, and their synergism can be used as an alternative to antibiotics in tilapia aquaculture.

The freshwater mussel (Lamellidens marginalis) was employed with a 28-day aquarium rearing of stinging catfish (Heteropneustes fossilis) exposed to a sublethal concentration (0.75 mg/l) of Pb(NO₃)₂ to evaluate the growth, Pb bioaccumulation, and associated liver histopathology in fish. Three treatments (T₂, T₃, and T₄) and a control (T₁) were assigned with 20 fish and 5, 20, 40, and 0 numbers of mussel each. The specific growth rate, percentage of weight, and length gain showed a larger increase of Pb in T₃ and T₄ than in the control and T₂. After 28 days, the highest amount of muscular and hepatic Pb was recorded as 2.43 ± 0.01 mg/L and 7.79 ± 0.8 mg/L respectively in the control group (T₁); the lowest amount was recorded in T₄ as 0.46 ± 0.07 mg/L and 4.41 ± 0.58 mg/L respectively. Liver histopathology exhibited vacuolization, raptured hepatocytes, blood congestion, necrosis, and fat droplets accumulation in different intensities. The control group manifested severe pathology; the T₄ treatment exhibited comparatively low signs.

This study aims to provide a thorough ecological understanding of fin fish diversity within carp spawning grounds in the Surma River and Tanguar haor. Over two spawning seasons, this research investigates ecological factors impacting fin fish diversity and abundance in carp spawning grounds of the Surma River and Tanguar haor, emphasizing water quality, habitat features, spawn availability, and environmental influences. Fish spawn samples were collected with eight “Savar nets” at chosen sites and reared in a fiberglass tank at the mini hatchery for species identification. The representative spawn samples were examined under a microscope for preliminary species identification before rearing. The study found that both the Surma River and Tanguar haor offer ideal conditions for carp spawning due to factors such as water quality, natural food availability, habitat suitability, and favorable climatic conditions. The study identified 39 fish species under the 10 fish groups from both locations, with a higher percentage of carp species (31.42%) in the Surma River in 2021 compared to 2022 (22.50%). In Tanguar haor, the percentage of carp species was 7.55% and 6.50% in 2021 and 2022, respectively. The Surma River’s ecological indices (2021-2022) indicated decreased diversity, likely due to environmental degradation, while Tanguar haor showed lower diversity possibly attributable to multiple environmental stressors. The dominant carp species, Labeo calbasu, Labeo bata, and Labeo gonius, were identified in both the Surma River and Tanguar haor. The spawning distribution varied among different locations, with some sites showing a presence of carp species, such as Hajipur in the Surma River and Alam Duar in Tanguar haor. The findings highlight the importance of hydrological and environmental parameters in shaping carp spawning habitat distribution and abundance, contributing to aquatic biodiversity conservation and resource management.

The Halda River and Haor basins are considered unique breeding habitats for carps in Bangladesh. The purpose of the study was to evaluate the natural spawning environment of carp species, with an emphasis on the hydrological conditions of the Halda River, the Surma River, and Tanguar Haor. This study, which covers the years 2021 and 2022, considered two spawning seasons. The results revealed that temperature, total dissolved solids (TDS), salinity, turbidity, conductivity, and pH were significantly different in the Halda River to the Surma River and Tanguar Haor. However, sudden rainfall and upstream runoff in 2021 were deemed as major factors causing an increment in TDS and electrical conductivity. The water pollution index was excellent in the Surma River and Tanguar Haor, and good in the Halda River. The study reported moderately reduced IMC fry production in 2021 because of inconsistent turbidity, high conductivity, and increased salinity which interrupted the ideal spawning habitat. However, in 2022, the spawning environment was favorable in the Halda River, while the Surma River and Tanguar Haor were considered to be comparatively favorable in both years. Differences were also found in the climatic and meteorological conditions, which revealed uneven rainfall, higher temperatures, decreasing water discharge, and low water levels. The meteorological data also revealed that the overall rainfall showed a decreasing trend for all sites in the last 20 years causing an interrupted water discharge. It was discovered that the amount of carp spawn obtained in the Halda River was greater than that obtained in the Surma River and Tanguar Haor. In terms of hydrological conditions and spawning performance, the Surma River and Tanguar Haor were reported to have significant differences, which may be due to their geographical location.