Catfish Heteropneustes Fossilis Research Articles

A histological observation on heavy metal induced implications on respiratory epithelium and its causative impact on a catfish Heteropneustes fossilis (Bloch)

Present study is based on lead nitrate induced histological effect on the respiratory organs of Heteropneustes fossilis (Bloch). Lead nitrate is a heavy metal compound which used in many industries and indiscriminately drains out in water system and contaminates aquatic medium leads serious hazardous effect on respiratory epithelium of fish. Lead nitrate induced alteration on respiratory epithelium associated with the air breathing organ, suprabranchial chamber and air sacs of Heteropneustes fossilis (Bloch) and also affect the oxygen consumption capacity of fish which adversely affect its survival. Heavy metal poisoning produced remarkable histopathological deleterious effect on the accessory respiratory organ decreases the rate of oxygen consumption. Various concentration of lead nitrate showed noticeable histopathological changes which is a sign of serious effect of this heavy metal and its bioaccumulation ultimately dangerous for human consumption of contaminated fish through food chain.

Influence of various carbon and nitrogen ratios in a jaggery-based biofloc rearing system on the Asian stinging catfish Heteropneustes fossilis

Biofloc technology (BFT) is becoming popular in aquaculture. As the human population has rapidly increased, so has the demand for protein, driving the expansion of aquaculture. The increased use of aqua medicines in aquaculture has led to resistant microbes. BFT offers a promising, eco-friendly solution by promoting beneficial microbes to improve fish health and reduce chemical use, supporting the industry's long-term sustainability. BFT recycles waste without water exchange by maintaining an optimal carbon-nitrogen (C:N) ratio and adding an external carbon source, which promotes the growth of heterotrophic bacteria and other essential microbes that absorb ammonia from feed and waste, forming beneficial microbial aggregates. This study evaluated the effects of various C:N ratios in a jaggery-based BFT system on water quality, growth, feed efficiency, and the well-being of Heteropneustes fossilis. A completely randomized design with triplicates (2.33 kg/m³ in 1500 L tanks) was used to compare a control group without biofloc to three BFT treatments with C:N ratios of 8:1 (CN8), 12:1 (CN12), and 16:1 (CN16) over 180 days. Daily feeding was conducted at 5–2 % of the fish's body weight (initial weight of 5.0±0.5 g). Higher C:N ratios were linked to reduced dissolved oxygen, ammonia, and nitrite levels, alongside increased total suspended solids, floc volume, and heterotrophic bacteria counts, while the CN12 had the highest levels of beneficial microbes (Firmicutes and Actinobacteria), leading to superior fish growth, survival, and biomass compared to CN8 and CN16. The CN12 also showed better stress response, hematology, immunity, and antioxidant properties. Histologically, fish in CN12 and CN8 had healthier liver and intestines compared to CN16 and control. The results suggest that a C:N ratio of 12:1 was optimal for biofloc systems used in cultivating H. fossilis, enhancing both microbial growth and water quality.

A Comparative Study of Electrophoretic Patterns of Proteins in Different Tissues of Fresh Water Cat Fish Heteropneustes fossilis (Bloch)

A Comparative Study of Electrophoretic Patterns of Proteins in Different Tissues of Fresh Water Cat Fish Heteropneustes fossilis (Bloch)

Dietary zinc requirement of juvenile stinging catfish Heteropneustes fossilis based on growth performance, haematology, and tissue mineral composition

This investigation was done to determine how much zinc (Zn) the stinging catfish, Heteropneustes fossilis, needs in its diet. Five isonitrogenous (34.5% protein) and isolipidic (6.0% lipid) diets were prepared to contain graded levels of Zn (0, 10, 20, 30, and 40 mg kg−1), supplied as zinc sulfate (ZnSO4·7H2O), and referred to as Zn0, Zn10, Zn20, Zn30, and Zn40, respectively. A total of 600 fish (initial body weight: 1.41 ± 0.02 g) were stocked in 15 glass aquaria (40 fish/aquarium), each with 180 L water capacity. For ten weeks, each diet was hand fed to three groups of fish twice daily until they appeared satisfied. The highest weight gain and specific growth rate, and lowest feed conversion ratio were recorded in fish fed with a 30 mg Zn kg−1 diet. Zn contents in bone and muscle linearly increased up to 30 mg kg−1 Zn and then remained stable, while iron (Fe) and copper (Cu) contents in bone and muscle had an inverse pattern with the inclusion level of dietary Zn. Increasing dietary Zn levels up to 30 mg kg−1 was found to improve values of hematological parameters such as red blood cell (RBC), white blood cell (WBC), haemoglobin (Hb), and haematocrit (HCT). These values, however, decreased when the dietary Zn level was further increased. The serum alkaline phosphatase level was the highest in fish fed a diet containing 30 mg kg-1 of Zn. Regression analyses based on weight gain, specific growth rate, and bone and muscle Zn concentrations indicated that the optimum dietary Zn requirement for stinging catfish was in a range of 27.4–36.5 mg kg−1.

Kisspeptin modulation of nonapeptide and cytochrome P450 aromatase mRNA expression in the brain and ovary of the catfish Heteropneustes fossilis: in vivo and in vitro studies.

In Heteropneustes fossilis, kisspeptins (Kiss) and nonapeptides (NPs; vasotocin, Vt; isotocin, Itb; Val8-isotocin, Ita) stimulate the hypothalamus-pituitary-gonadal (HPG) axis, and estrogen feedback modulates the expression of these systems. In this study, functional interactions among these regulatory systems were demonstrated in the brain and ovary at the mRNA expression level. Human KISS1 (hKISS1) and H. fossilis Kiss2 (HfKiss2) produced biphasic effects on brain and ovarian vt, itb and ita expression at 24h post injection: low and median doses produced inhibition, no change or mild stimulation, and the highest dose consistently stimulated the mRNA levels. The Kiss peptides produced an upregulation of NP mRNA expression at 24h incubation of brain and ovarian slices by increasing the concentration of hKISS1 and HfKiss2. The kiss peptides stimulated brain cyp19a1b and ovary cyp19a1a expression, both in vivo and in vitro. Peptide234, a Kiss1 receptor antagonist, inhibited basal mRNA expression of the NPs, cyp19a1b and cyp19a1a, which was prevented by the Kiss peptides, both in vivo and in vitro. In all the experiments, HfKiss2 was more effective than hKISS1 in modulating mRNA expression. The results suggest that the NP and E2 systems are functional targets of Kiss peptides and interact with each other.

Culture suitability of stinging catfish Heteropneustes fossilis in homestead tank: Selection of suitable stocking size

The present experiment was conducted for a period of 150 days to assess the effects of different stocking size on growth and production of stinging catfish (Heteropneustes fossilis) in three homestead cemented tanks (12×10×4 ft). Three different size groups of fish viz., 3.79±0.11, 3.09±0.13 and 2.53±0.18 cm was stocked at treatment T1, T2 and T3, respectively at a stocking density of 5000 individuals/tank each with three replications. Fish were feed twice daily with floating feed containing 35-40% protein at the rate of 15-10% for 1st 60 days, 8-6% for 2nd 60 days and 5-2.50% for rest of the culture period. The water quality parameters were within the suitable ranges for the fish culture. Mean weight gain (g) of stinging catfish was 49.03 ± 1.04, 36.72 ± 1.59 and 28.09 ± 0.41g, specific growth rate was 1.76 ± 0.02, 1.70 ± 0.04 and 1.66 ± 0.05 %/day in T1, T2 and T3, respectively. Food conversion ratio was 3.45 ± 0.82, 3.31 ± 0.10 and 3.30 ± 0.06 and survival rate were 90.67 ± 1.51, 88.20 ± 2.62 and 87.56 ± 1.26% in T1, T2 and T3, respectively. Higher stocking size also resulted in a significantly higher economic output in the form of benefit cost ratio (BCR) at T1 (2.13 ± 0.05) and the lowest at T3 (1.21 ± 0.03). The findings of the present study revealed that the highest weight gain and BCR was found in T1 which dictates that larger stocking size has a significant impact on better production.

Effect of water depth on growth and survival of the stinging catfish Heteropneustes fossilis (Bloch, 1794) in pond rearing system of a humid subtropical agroclimatic region

The growth, survival and proximate composition of Heteropneustes fossilis (Bloch, 1794) were studied under different water depths (30, 60, 90 and 120 cm) for a period of 10 months, with a temperature range of 31.5 to 7.8°C [(May-June; 26.5-31.5°C; Stage 1); (July-September; 28.8-32.6°C; Stage 2); (October-November; 15.5-28.4°C; Stage 3); (December-February; 7.8-15.7°C; Stage 4)] under earthen pond conditions in the humid subtropical climate of Tripura State, India. All the ponds were of equal size (168 m2; 14 m x 12 m) but with different water depths. The fishes were fed with a mixture of rice bran and mustard oil cake (1:1) @ 0.5-3% of their biomass. The growth, survival and proximate composition of fish were recorded in each stage. The average daily weight gain, feed conversion ratio, survival and proximate composition were found to be better in water depths of 60 cm and 90 cm during May to September when water temperature was ≥26.5°C. However, when water temperature was ≤21.4°C (October-February), growth and other attributes significantly reduced. Two-way ANOVA revealed that water depth and temperature, individually and interactively, affected the growth of H. fossilis. From this trial, it can be concluded that H. fossilis performs better when water depth is 60-90 cm and the ideal water temperature for the culture is 28.3-30.4°C. The study confirms the depth preference of H. fossilis under the humid subtropical condition and the information generatedwill help in the sustainable farming of this species. Keywords:Asian stingingcatfish, Water depth,Temperature, Growth, Survival, Proximate composition

Optimisation of sperm cryopreservation protocol for Asian stinging catfish Heteropneustes fossilis (Bloch, 1794), to support hatchery seed production

The present study experimentally evaluated different parameters such as extender composition, storage duration and egg to sperm ratio to optimise parameters for sperm cryopreservation in Asian stinging catfish Heteropneustes fossilis. Four extender compositions viz. Hanks Balanced Salt Solution (HBSS), Modified HBSS (M-HBSS), Modified HBSS with hen’s egg yolk (M-HBSS with EY) and European catfish extender were evaluated for sperm cryopreservation with dimethyl sulphoxide (DMSO) as cryoprotectant (10% v/v). The hatching rate was used as standard to evaluate the fertility of thawed sperm at different periods of storage (2, 270 and 668 days). After 2 days, extender M-HBSS exhibited highest hatching rate (49.06±2.67%) which was comparable to the control value (51.00±7.23%), followed by HBSS (42.76±32.0%), M-HBSS with EY (37.46±24.34%) and European catfish extender (29.47±25.61%), respectively. After 270 days with M-HBSS, hatching rate was 64.34±8.84% similar to the control; however, cryopreserved sperm with other extenders exhibited lower hatching rate as compared to control and M-HBSS. After 668 days, sperm cryopreserved in the extender M-HBSS, only yielded successful hatching. Results indicated that presence of egg yolk in the extender M-HBSS did not improve the performance of cryopreserved sperm. The successful hatching using cryopreserved sperm after 270 and 668 days of storage indicates M-HBSS as a useful extender for sperm cryobanking and seed production of H. fossilis. Keywords: Aquaculture, Cryopreservation, Cryoprotectant, Dimethyl sulphoxide, Extender, Hanks Balanced Salt Solution, Hatching rate

Dietary manganese requirement of stinging catfish Heteropneustes fossilis

The study was aimed to determine the optimal dietary manganese (Mn) requirement by evaluating the effects of various dietary Mn levels on the growth performance, whole-body chemical composition, bone mineralization, and haematology of juvenile stinging catfish Heteropneustes fossilis. Five isonitrogenous purified diets containing graded levels of supplemental Mn from MnSO4.H2O (0, 5, 10, 15 and 20 mg Mn kg−1) were formulated, and referred to as Mn0, Mn5, Mn10, Mn15, and Mn20, respectively. Fish (mean weight of 1.24 g) were stocked in 15 glass aquaria (40 fish per aquarium) each of 180 L water capacity. Each diet was hand-fed twice a day (9.00 and 16.00 h) to apparent satiation to triplicate groups of fish, 7 days a week for 10 weeks. Results indicated that significantly (P < 0.05) the highest % weight gain (186.65 ± 6.59 g) and specific growth rate (1.59 ± 0.13 % day−1) were observed in the fish fed with Mn10 diet supplemented with 10 mg Mn kg−1 diet. The fish feed with Mn10 diet had significantly the lowest (1.80 ± 0.16) feed conversion ratio (FCR). Incorporating dietary Mn up to 10 mg kg−1 was reported to boost whole-body protein; however, subsequent increases in dietary Mn inclusion level did not result in any changes. The whole-body moisture and lipid contents of stinging catfish dropped significantly (P < 0.05) when fed with 10 mg kg−1 Mn (Mn10) supplemented diet. The concentration of Mn in muscle and bone rose linearly (P < 0.05) up to the dietary intake of 10 mg Mn kg−1 diet and then it remained stable. The amount of iron (Fe) in bone and muscle was found to decrease as dietary supplementation level of Mn increased. Increasing dietary Mn levels up to 10 mg kg−1 was found to increase haemoglobin (Hb), red blood cells (RBC), white blood cells (WBC), and mean corpuscular haemoglobin (MCH); however, further increase in dietary Mn levels caused these values to decrease. The amount of dietary concentration between 7.99 and 10.38 mg Mn kg−1 diet was revealed to be acceptable for culture stinging catfish by applying the second-order polynomial regression analysis. It is concluded that better growth and physiological status of stinging catfish can be ensured by using optimum Mn levels in the diet. The results of this study will also motivate further research into the dietary Mn requirements of other species.

Catecholamines modulate differentially nonapeptide precursor mRNA expression in the preoptic area and ovary of the catfish Heteropneustes fossilis: An in vitro study

In the catfish Heteropneustes fossilis, three nonapeptide hormone genes were identified in the brain preoptic area (POA) and ovary: a pro-vasotocin (pro-vt) and two isotocin gene paralogs viz., a novel pro-ita and conventional pro-itb. In the present study, the regulatory role of catecholamines [CA: dopamine (DA), noradrenaline (NA), adrenaline (AD)] on the expression of these genes were investigated in vitro. DA (1, 10, and 100 ng/mL) inhibited significantly the mRNA expression in both the POA and ovary. NA upregulated the POA mRNA expression in a biphasic manner, the lower concentrations (1 ng and 10 ng) scaled up and the higher concentration (100 ng) scaled down the expression of pro-vt and pro-itb, while only the 1 ng NA scaled up the pro-ita expression. In the ovary, NA upregulated the mRNA expressions at all concentrations; the pro-vt expression was stimulated only at 10 and 100 ng. AD stimulated pro-vt and pro-ita expression in the POA at all concentrations but the pro-itb expression was inhibited at 1 and 10 ng, and stimulated at 100 ng concentrations. In the ovary, AD elicited varied effects; no significant change in pro-vt, a stimulation of pro-ita, and an inhibition of pro-itb at 1 ng, and stimulation of pro-itb at the 10 and 100 ng. The incubation of the POA and ovary with α-methylparatyrosine (MPT, 250 µg/mL, a tyrosine hydroxylase inhibitor) for 8 h downregulated the mRNA expression in the POA but unaltered the expression in the ovary. Pre-incubation with MPT for 4 h, followed by co-incubation with DA, NA or AD for 4 h elicited varied effects. In the POA, the co-incubations with the CAs rescued the inhibition due to MPT. The MPT + DA and MPT + AD treatments reduced the magnitude of the inhibition of pro-vt and pro-itb by MPT. But the pro-ita expression was modestly stimulated in the MPT + AD group. On the other hand, the MPT + NA treatment rescued the MPT effect and elicited 10-folds increase in the expression levels. In the ovary, the changes were: an inhibition in the MPT + DA group, no significant alteration in the MPT + NA group, and a mild stimulation in the MPT + AD group. The results suggest that CAs modulate brain and ovarian nonapeptide gene expression differentially, which is important in the neuroendocrine/endocrine integration of reproduction in the catfish.

A Male Hormone-Induced Changes in Growth Performance and Histopathology in the Stinging Catfish Heteropneustes Fossilis (Siluriformes: Heteropneustidae) Under Laboratory Conditions

The present study was conducted to assess the features of the stinging catfish Heteropneustes fossilis (Bloch) in terms of total length (TL), total weight (TW) and growth performance and survival rate after treatment of fish feed with a synthetic male hormone, 17 α-methyltestosterone (17 α-MT) under laboratory conditions. Results showed that TL in the untreated (C) and T1 group of fishes differed significantly (p&lt;0.05) even though the overall effect of the hormone did not influence TL of the fishes under study (p = 0.085). A similar result was observed for TW, but the overall impact of 17-αMT on TW of H. fossilis was highly significant one (p&lt;0.001), indicating that the TW was increased much more than the TL due to the hormone treatment in the experimental fishes. Growth performances of the fishes in terms of their gains in TL and TW due to the hormone treatment and over a rearing period of four months from March to June showed that compared to the control groups, all three treatment groups increased in both the morphometric parameters in H. fossilis. The increases in TW were more drastic than the corresponding increases in TL. Notably, the hormone treatments did not affect the survival of the experiment fishes under study. Histopathological changes in the intestine of T2 fishes were characterized by hemorrhage and degeneration of villi, whereas hemorrhage, degeneration of serosa and rapture of villi were remarkable in T3 group. Enlarged glomeruli, lots of vacuoles, disorganization of renal tubules and necrosis were observed in T2 whereas the T3 group was characterized by vacuoles, disorganization of tubules, enlarging glomeruli and wider tubular lumen. Since the present results clearly demonstrated that 17 α-MT treatments enhanced the total length and weight as well as growth performance of H. fossilis, carefully designed experiments with appropriate doses of the hormone in fish feed would be beneficial for the commercial production and conservation of this popular catfish in the country. J Bio-Sci. 30(1): 131-141, 2022 (June)

Localization of Acetylcholine, Alpha 7-NAChR and the Antimicrobial Peptide Piscidin 1 in the Macrophages of Fish Gut: Evidence for a Cholinergic System, Diverse Macrophage Populations and Polarization of Immune Responses

The recognition and elimination of invading pathogens are vital for host survival. Macrophages play a central role in host protection and cells functionally reminiscent of vertebrate macrophages are present in all multicellular organisms. A pattern responsible for bacterial recognition found on the surface of macrophages is CD14. These cells possess a repertoire of antimicrobial molecules stored in their granules and lysosomes. Polarization states observed in mammalian macrophages termed M1 and M2 also likely exist in fish macrophages. Markers for macrophage subtypes are slowly but definitively emerging in fish species. In the present study cell markers such as CD14, acetylcholine, alpha 7 acetylcholine nicotinic receptor (nAChR) subtype, the inducible nitric oxidase synthase (iNOS), and the antimicrobial peptide piscidin 1 are reported for the first time in the intestinal macrophages of both catfish Heteropneustes fossilis (Bloch, 1794) and the African bonytongue Heterotis niloticus (Cuvier, 1829) along the anterior and the posterior axis and the concentric muscle layers. Many antimicrobial effector responses of vertebrate macrophages including respiratory burst and NO induction are similar across the diverse animal taxa. Antibodies against calbindin coupled with ones to VAChT and tubulin revealed the localization of myenteric and submucosal plexuses, which are made up of enteric neurons, glial cells, and nerves near macrophages. Current studies allow for the elucidation of multiple roles of macrophages in disease models providing an insight into their in vivo function in fish.

Replacement of fish meal by Lucilia sericata (Meigen, 1826) live larvae and powdered meal in production of stinging catfish Heteropneustes fossilis (Bloch, 1794) post-larvae

Replacement of fish meal by Lucilia sericata (Meigen, 1826) live larvae and powdered meal in production of stinging catfish Heteropneustes fossilis (Bloch, 1794) post-larvae

Culture and production of Lucilia sericata Meigen (1826) larvae for rearing stinging catfish Heteropneustes fossilis (Bloch, 1794) using poultry waste

The fly larvae (Lucilia sericata) are being used as an alternative protein source in any kind of animal feed as it reduces the cost of preparation of feed. This current study focused on the physico-chemical and proximate properties of raw poultry waste, while this study also revealed the production process of fly larvae and the proximate composition of it. The poultry waste was collected from Suvro poultry farm, Sutiakhali, Mymensingh, then the physic-chemical properties of the raw poultry waste were determined using different procedures. Three treatments were considered for production of fly larvae, T1 (3 kg), T2 (6 kg) and T3 (9 kg) in a 15 kg capacity tray with three replications. After production, the proximate composition were also measured of fly larvae. Physico-chemical properties such as, color, odor, texture, temperature, pH, total solids (TSS+TDS), chemical oxygen demand, dissolved oxygen, alkalinity, available N, available P, and fiber in raw poultry waste were determined and presented. Proximate composition such as, moisture, total N, total P, available N, total Ca, ash and crude fiber were found in significant amount in the poultry waste. It was found that T3 (1350±68g) produced highest volume of live maggot compared to the other treatments, but T2 (17.50±1.10%) produced highest percentage volume. The proximate compositions of fly larvae were assessed and found 56.60±0.25% protein value in it, suggesting that fly larvae could be the protein replacer in fish feed. The result of this study revealed cheap protein source in aquaculture production, such as production and rearing of stinging catfish Heteropneustes fossilis, and the findings might be helpful for cost reduction in aquaculture operation. Asian J. Med. Biol. Res. 2022, 8 (4), 216-224

Histopathological changes in the gonads of a freshwater catfish Heteropneustes fossilis following exposure to cadmium

Histopathological changes in the gonads of a freshwater catfish Heteropneustes fossilis following exposure to cadmium

Transcriptome analysis of gills reveals novel insights into the molecular response of stinging catfish (Heteropneustes fossilis) to environmental hypertonicity

The stinging catfish Heteropneustes fossilis is a champion survivor under hypertonic stress and is suggested to be a profitable candidate for culture in slightly saline water in coastal regions. Fish gills are an essential site of osmoregulation and other physiological processes. To investigate the stress responses and mechanisms of salinity tolerance in stinging catfish, we sampled gills tissues from control and hypertonicity (100 mM NaCl solution) treated adult catfish and assessed for transcriptomic profiling by high throughput sequencing. The raw data generated was filtered and assembled for de novo transcriptome assembly. The final contig assembly produced a total of 1,71,478 unigene transcripts with an average transcript length of 898 bp and a GC content of 45%. A total of 22,231 transcripts matched with Chordata with BLAST search and were functionally annotated, out of which 21,814 were best-hit transcripts aligned with the UniProt database. Comparative transcriptomic analysis revealed that a total of 1951 genes were differentially expressed in the gills of NaCl-treated fish compared to the control. Functional and enrichment analysis of the Differentially expressed genes demonstrated that several GO pathway terms were significantly over-represented, such as 'catalytic activity', 'hydrolase activity' in molecular function category, 'membrane', 'integral component of membrane' in cellular component category and 'metabolic process', 'regulation of transcription' in biological process category. The functional analysis study of DEGs demonstrated that tolerance to hypertonic stress by stinging catfish is associated with a few pathways related to stress response, immune response, biosynthesis, metabolism, molecular transport, cytoskeleton remodeling, apoptosis, cell signaling, transcriptional regulation, etc. The present study provides a novel insight into the molecular responses of the air-breathing stinging catfish against salinity stress, which could elucidate the underlying mechanisms of adaptation of this stenohaline species under various environmental constraints.

A Comparison of Artificial and Natural Diets for Growth and Survival of Stinging Catfish Heteropneustes fossilis Larvae

A Comparison of Artificial and Natural Diets for Growth and Survival of Stinging Catfish Heteropneustes fossilis Larvae

Effects of carbon-nitrogen ratio manipulation on the growth performance, body composition and immunity of stinging catfish Heteropneustes fossilis in a biofloc-based culture system

A 10-week indoor culture study was done to evaluate the effects of varying C/N ratios on growth performance, body composition, immunity, and haematology of stinging catfish Heteropneustes fossilis cultured in zero-water exchange culture tanks. Biofloc-based tanks with four levels of C/N ratio (12, 15, 18, 21) via the addition of carbohydrate referred to as ‘CN12′, ‘CN15', 'CN18' and 'CN21', and freshwater tanks operated with the facility of water exchange and without the addition of carbohydrate referred to as 'Control' (CN10). Fish (average weight 0.60 g) were stocked in 15 experimental tanks with 300 L water capacity and fed a commercial diet containing 30 % crude protein. The water quality parameters (pH, temperature, total ammonia nitrogen, nitrite nitrogen, dissolved oxygen, total suspended solids, and total dissolved solids) were monitored throughout the experiment. There was no significant (P > 0.05) difference among the treatments in the case of DO and temperature. The pH, total ammonia nitrogen, and nitrite nitrogen contents decreased with increasing C/N ratio, whereas the total dissolved solids and total suspended solids increased with gradually increasing the C/N ratio. Compared to the control, the treatment CN15 resulted in a 72 % and 34.4 % higher percent weight gain and specific growth rate, respectively. CN15 treatment resulted in improved feed utilization, as measured by feed conversion ratio (1.32 ± 0.07) and protein efficiency ratio (1.36 ± 0.10), which were 36.2 % lower and 54.5 % higher, respectively, than control. However, there were no differences in growth performance and feed utilization data between CN15 to CN21. Increasing the C/N ratio increased the body protein and ash contents and decreased the moisture and lipid contents compared to control. In the serum lysozyme test, the lysozyme value increased with a gradually increasing C/N ratio, and a better result was found in the CN15-CN21 treatments (15.58–15.74 µg ml−1) compared to the control (12.45 µg ml−1). At the end of the rearing period, fish were subjected to a challenge test with Aeromonas hydrophilla to determine the mortality rate where mortality was the lowest in CN15 treatment. Furthermore, increasing the C/N ratio from 15 to 21:1 showed better results for haemoglobin, white blood cells, red blood cells and hematocrit values. Overall, the manipulation of the C/N ratio from 15 to 21:1 revealed suitable for the feed utilization, growth performance, body composition, and immunity of stinging catfish. Therefore, maintaining a C/N ratio of 15:1 can be recommended for the culture of stinging catfish in the biofloc system.

Dichlorodiphenyltrichloroethane (DDT) residues status in fishes and prawns of Chittagong chemical complex area, Bangladesh

Fourteen various fish samples i.e., rui Labeo rohita, catla Gibelion catla, striped dwarf catfish Mystus vittatus, stinging catfish Heteropneustes fossilis, walking catfish Clarias batrachus, Ganges river sprat Corica soborna, mola carplet Amblypharyngodon mola, common carp Cyprinus carpio, Nile tilapia Oreochromis niloticus, climbing perch Anabas testudineus, spotted snakehead Channa punctatus, striped snakehead Channa striata, bronze featherback Notopterus notopterus, wallago catfish Wallago attu and mixed juvenile prawns were collected from a pond of closed down DDT (Dichlorodiphenyltrichloroethane) factory area of Chittagong Chemical Complex (CCC) of Bangladesh to assess the concentrations of DDT and its metabolites (4,4'-DDD and 4,4'-DDE). The fish flesh and shell-free prawn muscle samples were extracted by QuEChERS method and these were cleaned up using H2SO4. The cleaned sample extracts were analyzed using a Gas Chromatograph coupled with Electron Capture Detector (GC-ECD). The cultured L. rohita was used as a control which was found to contain no detectable amount of DDTs. Recovery experiments with control samples were spiked with certified DDTs standard at three different concentrations (0.01 mg kg-1, 0.02 mg kg-1 and 0.05 mg kg-1) levels. The percent recoveries were 72-114 % (0.05 mg kg-1), 70-101 % (0.01 mg kg-1) and 87-105 % (0.02 mg kg-1). LOD and LOQ of the standards were found to be 0.0625 μg kg-1 and 0.2063 μg kg-1, respectively and R2 of 4'-DDE, 4,4'-DDD, 2,4'-DDT and 4,4'-DDT were found to be 0.999, 0.999, 0.999 and 0.998, respectively. The concentrations of total DDTs residue in fish and prawn samples ranged between 0.66 ng g-1 in W. attu to 8.90 ng g-1 in H. fossilis. The ratios of 4,4'-DDT/ΣDDTs in the studied fish samples indicated the historical use of DDTs in the adjacent region around the DDT factory of the CCC area. The concentrations of total DDTs in all the samples were within the permissible Maximum Residue Level (MRL) recommended by FAO-WHO. To assess human health risks, Health risk Indexes (HI) of fish and prawn samples were calculated. HIs&lt;1 in all fish and prawn samples indicated that the fish samples are safe to consume but the daily consumption of the fish together with other contaminated food may cause human health hazards. Bangladesh J. Zool. 49 (3): 381-391, 2021

Impact of ovariectomy and estradiol-17β (E2) replacement on the brain steroid levels of the Indian stinging catfish Heteropneustes fossilis

In the present study, effects of ovariectomy (Ovx) and estradiol-17β (E2) replacement on the brain steroid levels were investigated in the resting and prespawning phases of the female catfish Heteropneustes fossilis. The study showed that Ovx resulted in significant decreases in plasma levels of estradiol-17β (E2) and its precursors, and the effect varied with the reproductive stage and duration. Our study showed that E2 supplementation reversed the effect of Ovx in 3-week Ovx fish group, either restored or increased according to the dose. In contrast, E2 levels increased in the brain after Ovx in the resting stage and produced a biphasic effect of significant decreases on week 1 and 2, and significant increases on week 3, 4 and 5 in the pre-spawning stage. The brain E2 levels significantly inhibited in E2 supplementation groups. The testosterone (T) levels showed biphasic effects, an initial decrease (up to 3 weeks Ovx) and an increase later (week 4, 5) in the resting stage. In the pre-spawning stage, the T levels increased significantly after Ovx. The E2 supplementation significantly inhibited the T levels, more severely in the low dose group in the resting and pre-spawning stages. Brain 17-hydroxyprogesterone(17-OHP4) levels increased (week 1, 2, 3) but decreased on week 4 and 5 of Ovx in the resting stage and increased throughout Ovx in the pre-spawning stage except in the 5th week (though compared to other steroids, level was very low; almost negligible). The E2 replacement significantly decreased the steroid levels further down compared to the Ovx control group. Brain progesterone (P4) and pregnenolone (P5) levels decreased initially (week 1 and 2 Ovx) and recovered later. The E2 replacement significantly decreased P4 levels in the Ovx fish in the pre-spawning stage and in the lower dose group in the resting stage. The P5 levels remained inhibited after the E2 supplementation in the resting stage but unchanged or increased it in the pre-spawning stage. Brain cortisol (F) levels were inhibited initially (1 and 2 weeks and later increased after OVX in the resting stage. In the pre-spawning stage, the F levels increased in the week 1, 2 and 3 of Ovx and decreased in the 4th and 5th weeks. The E2 supplementation inhibited the cortisol (F) levels in both phases. The results show that ovarian steroids influence neurosteroidogenesis in a reproductive stage-dependent manner.