Fish Weight Research Articles

The role of dietary vitamin A in mechanisms of cataract development in the teleost lumpfish (Cyclopterus lumpus L).

Lumpfish (Cyclopterus lumpus L) are highly prone to cataract development in the wild and in culture. There is evidence that cataract in farmed fish is related to nutrition. However, both the nutrients and the mechanisms involved in cataract development in lumpfish are not clear. Here we investigated the mechanisms involved and the role of dietary vitamin A in cataract development in a cultured lumpfish population. Cultured lumpfish were fed three diets differing only in vitamin A supplementation level (5000, 15,000 and 120,000 IU/kg) over an 18-month period, and fish weight, cataract frequencies and severities were determined. Western blotting and immunohistochemistry were performed on lens tissue to measure the levels of oxidative stress, and apoptosis. The lowest levels of vitamin A significantly reduced cataract frequencies in adult lumpfish and resulted in less severe cataract and increased weight in males. Oxidative stress levels in the lens were positively correlated with vitamin A intake. Apoptosis was observed at high levels in lenses with severe cataract. Oxidative stress and apoptosis levels were the highest in regions of the lens with severe, advanced cataract pathology when compared to regions with no visible pathology. These results suggest that higher vitamin A intake contributes to cataract development through an oxidative stress pathway, and that both oxidative stress and apoptosis are involved in advanced stages of cataract in lumpfish.

Farmed Atlantic salmon (Salmo salar L.) avoid intrusive objects in cages: The influence of object shape, size and colour, and fish length

Underwater vehicles and other mobile platforms are seeing increased use as tools within fish farming, particularly due to current trends towards Precision Farming practices, and more exposed farming sites. Although many of the applications of such tools (e.g., net cleaning and inspection) have become well established industrial practices, it is largely unknown how much such operations disturb the fish and the consequence of this disturbance. In this study, we explored this by exposing Atlantic salmon in commercial net cages to intrusive objects and monitoring the distribution of fish around these using on-board 360-degree sonars. Six different object designs were tested covering variations in size, shape, and colour, which are important static characteristics of underwater vehicles/platforms. The sonar data was first aggregated into images containing the Cumulative Fish Presence over 1-, 5- and 10-min periods to provide a more robust foundation for further analyses. By training a deep learning based method using UNet++ architecture to automatically segment the fish distribution patterns, the mean distance between the inner perimeter of the fish distribution and the object was assessed. Results from the study implied that fish keep greater distances to larger objects. There was, however, no clear impact of the shape. Regarding the effect of colour, fish kept greater distances to yellow than to white objects. When comparing results from tests on fish of different size, data indicate a positive linear relationship between fish weight (age) and distance to an object, that can be expressed as an avoidance distance of an average 3.8 body-lengths. Our findings provide new fundamental knowledge on the dynamics between the fish and objects such as vehicles or other mobile platforms in fish farms, and thus provides valuable insights that can be useful when designing such tools specifically for aquaculture.

Effects of Short-Term Intermittent Fasting on Growth Performance, Fatty Acids Profile, Glycolysis and Cholesterol Synthesis Gene Expression in European Seabass Dicentrarchus labrax

The present study was applied to evaluate the effects of alternate feeding and feed restriction on gene expression, growth, proximate composition and biochemical indices in European seabass, Dicentrarchus labrax. Fish were randomly divided into six indoor tanks with 90 fish per tank in a recirculating aquaculture system. Two feeding strategies were applied, in which the first group was fed daily to satiation and the second was intermittently fed (8 days feeding to satiation–2 days starvation) for 40 days. At the end of the experiment, outlier fish were sorted as fast growers (FG) and slow growers (SG) according to their final body weight. The differential gene expression tested was related to glycolysis (pk, ldha, hk, g3pdh, eno1 and alda), fatty acid metabolism (lpl and acc) and cholesterol synthesis (7dhcr and sqle). In addition, muscle ldha and gpi expressions were positively correlated with fish weight. The concentrations of glucose, triglycerides, cholesterol and non-esterified fatty acids (NEFA) were not affected by the dietary treatments. Glucose and NEFA differed significantly between SG and FG fed groups. Overall, the physiological responses of glucose and fatty acid metabolism in fish, as recorded by gene expression assays, were triggered by minor interventions in feeding rather than the different growth rates. Expression of specific genes and biochemical parameters could be used as potential biomarkers to improve aquaculture practices and benefit fish husbandry through selective breeding, feeding strategies and farm management. The study provides new insights on the impact of intermittent feeding of European seabass, with gene markers and their potential effects, for European seabass aquaculture.

Chitosan- hypothalamic hormonal analogue nanoconjugates enhanced the reproductive performance in Indian major carp, Labeo rohita

The current study reports the potential of chitosan nanoparticles for the efficient delivery of hypothalamic hormonal analogue in Labeo rohita, aiming to improve reproductive performance. Here salmon gonadotropin-releasing hormone analogue (sGnRH-a) was conjugated with chitosan nanoparticles (ChN-sGnRH-a) to evaluate its efficiency in enhancing the reproductive gene expression, hormones as well as the overall reproductive output in L. rohita. A total of 54 pairs of brooders were selected and divided into six treatments viz; C0: Negative Control (fish injected with bare chitosan nanoparticles), C: Positive Control (fish injected with Gonopro-FH®, a commercially available inducing hormone, at a dose of 0.2 ml/kg body weight of fish), T1: fish injected with ChN-sGnRH-a at a dose of 0.2 ml/kg, T2: T1 + 10 mg/ml domperidone, T3: fish injected with ChN-sGnRH-a at a dose of 0.1 ml/kg, T4: T3 + 10 mg/ml domperidone. In T2 and T4 treatments, serum hormones, Testosterone (T); Estradiol (E2); Vitellogenin (Vtg); and 17α, 20β-dihydroxyprogesterone (17α, 20β-DHP) showed the sustained elevation. The means of reproductive traits like fecundity, fertilization rate, pseudo-gonadosomatic index and spawning rate were significantly (P<0.05) higher in T2 treatment, while no significant difference was found between C and T4 treatment. The mRNA expression level of follicle-stimulating hormone (fshβ), luteinizing hormone (lhβ) and their cognate receptors was significantly better in T2 treatment, while no significant difference was found between T4 and C treatments. Further, the histological analysis of ovaries showed increased post-ovulatory follicles in C, T2 and T4 treatments. The results indicate that ChN-sGnRH-a could help in reducing the recommended dose of sGnRH-a without affecting the reproductive performance in L. rohita females. The sustained releasing mechanism of this formulation may be used as an induced breeding strategy in female L. rohita broodstock.

Growing smaller fish for inclusive markets? Increasing stocking density and shortening the production cycle of Nile tilapia in cages on Lake Victoria

Fish farmers aim to maximise fish weight relative to the feed inputs needed to turn a profit. Yet, many farmers in Africa lack the cash flow to grow large fish and many consumers prefer, or are limited to purchasing, small fish. This study aimed to intentionally produce small tilapia in cages by assessing the effects of higher stocking densities and shorter growth cycles on production and financial efficiency. An experiment with 3 treatments and 6 replicates took place on Lake Victoria. The first treatment (T1) used a stocking density of 2.9 ± 0.3 kg per m−3 and aimed to produce fish to an average body weight (ABW) of 400 g (final ABW = 500.33 ± 31.01 g after 138 days). Treatment two (T2) did the same but with double the stocking density (5.9 ± 0.3 kg per m−3), resulting in a final ABW of 439.22 ± 22.22 g over 138 days. The third treatment (T3) partially harvested 50% of the cage (after 76 days) once reaching an ABW of 230.92 ± 22.55 g. The remaining fish in T3 were on-grown for a total of 138 days (final ABW = 499.86 ± 15.95 g). A fourth production scenario (M1) based on data from T3, modelled a 100% harvest after 76 days of culture. There were no significant differences in mortality between treatments. There were no statistical differences in the feed conversion ratio (FCR) between T1 (1.51 ± 0.03) and T2 (1.49 ± 0.02), though T3 was statistically lower (1.46 ± 0.02; p = 0.03). Cages in T1 had a higher proportion of fish between 400 and 599 g while fish in T2 were mostly between 300 and 499 g. T3 had a bimodal distribution with most fish either in 200–299 g or 400–499 g. There was little effect on average price per kg for T1 (3.0 ± 0.01 USD) and T2 (2.98 ± 0.01 USD), though T3 (2.89 ± 0.04 USD) was significantly lower (p = 0.001). Overall, T2 had significantly higher gross margins (17% ± 2.08) than T1 (13% ± 2.3, p = 0.021) and T3 (7.2% ± 2.43, p = 0.001), while M1 had the lowest gross margins (−11.8% ± 5.5). The results suggest that farmers can increase stocking densities. Some farmers can use partial harvesting strategies or shorter cycles to produce small tilapia and achieve faster cash flows, though the economic margins are lower. Such approaches can provide opportunities for poorer farmers and consumers.

FEMALE BROODSTOCK SIZE AND MATERNAL EFFECTS ON PROGENY OF Clarias gariepinus (BURCHELL 1822)

Catfish farmers have been enduring having to spawn with very big females at high cost avoiding medium and small sizes. The relationship between female broodstock weight and the growth rate of progeny has been a major concern among catfish producers. To examine the impact of different female broodstock sizes on the reaction to growth of the fish seed, induced breeding of the study fish was done. The experiment was designed a completely randomized design (CRD) made of three treatments replicated three times. The treatment were three categories of weight of broodstocks as Treatment I (1000g (Treatment I or Small size), Treatment II (1500g or Medium size) and Treatment III (2500g or Large size). There was no significant fluctuation in the physico-chemical parameters of the water. There was no significant difference in the fry survival among Treatments (P>0.05). The maternal effect on growth of the study fish was 10.5 weeks of culture as Treatment 11 fingerlings then grew fastest. At the end of 40 weeks culture period there was significant difference (P<0.05) in the final weight of the table fish (1231.67 g, 1156.67g, and 1006.67g, for Treatment 11, Treatment 111, and Treatment 1, respectively). Overall, the results of these growth evaluations showed that the selected group had improved growth performance. Medium sized female broodstock can therefore deliver substantial genetic improvements in induced breeding of the study fish.

Heavy metal concentrations in various tissues of two fish species from Damsa Dam Lake (Turkey) and associated health risk assessment

Purpose of review and methodIn this study, indicate the average or range of 10 heavy metal concentrations in muscle, gills and liver of two fish species (Squalius pursakensis and Cyprinus carpio) living in the Damsa Dam Lake (Turkey) was examined in relation to fish gender and size. Inductively coupled plasma-tandem mass spectrometry was used to evaluate the concentrations of heavy metals. The average contents of the metals in S. pursakensis muscle samples were 0.877, 9.285, 0.614, 0.488, 8.190, 0.155, 0.015, 0.010, 0.218, 0.009 mg/kg for Cu, Fe, Mn, Ni, Zn, As, Cd, Co, Cr and Pb respectively. On the other hand, the average contents of the metals in C. carpio muscle samples were 0.673, 8.001, 0.367, 0.435, 6.107, 0.188, 0.007, 0.007, 0.371, 0.012 mg/kg for Cu, Fe, Mn, Ni, Zn, As, Cd, Co, Cr and Pb respectively. In addition, human health risks were evaluated considering the estimated daily intake of heavy metals in adults. The target hazard quotient, hazard index and carcinogenic risk values were determined based on the frequency of fish consumption for the population living in the region. Result and conclusionThe highest quantities of all heavy metals were determined in the gills and liver of the fish species. The levels of most heavy metals in tissues did not differ significantly between both fish species. Only a few heavy metals in the tissues of both fish species demonstrated significant associations with fish length or weight. In terms of the levels of most of the heavy metals in the tissues, there weren’t any significant differences between the male and the female fish. The estimated daily intakes of all of the heavy metals were lower than the reference doses. The values of the target hazard quotient and the hazard index were found to be below 1 and the values regarding carcinogenic risk were assessed to be within or lower than the permissible levels. Cr, Cu, Zn, Cd, Pb and inorganic As values assessed in the muscle tissues of fish were found below the values acceptable by national and international institutions. These results proved that the examined fish species can be consumed safely.

Enhancing Water Quality Management in Ornamental Fish Aquariums with Pot and Bamboo Filter Systems

The filtration of aquarium wastewater composed of a pot and bamboo is constructed for the purification of microbial activities and to reduce turbidity. The aquarium wastewater is treated with sand to reduce BOD and COD; the usage of coconut husk and vetiver act to decrease the turbidity, nitrite, and pH while raising DO level. Initially, sand was sieved to produce 12 size ranges between 180 and 2000 m. The effectiveness of each range in removing turbidity, BOD, and COD through sand beds 4 or 5 cm deep were tested. The critical size (300 & 425 m) at which no solid particles could penetrate through the sand bed was observed at 3 and 4 cm in depth, respectively. Moreover, the flow of solids through sand filter beds had all particles smaller than 180 m removed from them. A 2 cm bed of sand allowed 0.2-0.5% of solids to flow through, and a 4 cm bed allowed 0.07-0.1 %. Both fine and coarse sand layers are supported by a layer of gravel. In the column approach, the thickness and flow rate of each layer were fixed. The thickness of the layers of sand and charcoal were fixed at 4 cm and 6 cm, respectively. The findings of the column analysis, the combined filter showed decreases in turbidity by 48%, COD by 52%, BOD by 30%, and increasing DO by 48%, respectively. The results reveal that absorbing nutrients can serve as bio-filters to create better conditions for fish growth. The final weight, length, and SGR of fishes in the three aquariums were significantly different after seven weeks of trial, the treated aquarium showed the highest value than the control.

Dietary propolis improves the growth performance, redox status, and immune response of Nile tilapia upon a cold-stress challenge.

The purpose of this research was to demonstrate the potential of adding propolis (PR) to the diet of Nile tilapia (Oreochromis niloticus) to mitigate the harmful effect of cold stress (CS) on the growth performance, redox status, and immunological response. Two trials were conducted in this study. First, 210 Nile tilapia fingerlings (28.61±0.20 g) were used in a preliminary trial to determine the appropriate PR level and supplementation period to be applied for the main trial. Fish were assigned into 7 treatment groups (3 aquaria replicates × 10 fish per aquarium in each treatment group) according to the rate of PR supplementation in the fish diets at 0, 2, 4, 6, 8, 10, and 12 g/kg for 6 consecutive weeks. The average body weight and body weight gain were determined weekly. It was found that PR supplementation at 10 g/kg in fish diet for 4 weeks was enough to obtain significant results on the growth performance of Nile tilapia. For the main trial of the present study, 480 Nile tilapia fingerlings (average weight 29.93±0.11 g) were distributed into randomized 2 PR × 2 CS factorial treatment groups (6 replicate aquariums containing 20 fish in each group). Fish of PR groups received a basal diet for a feeding period of 4 weeks, included with 10 g/kg PR (+ PR group) or without PR inclusion (- PR group). Fish of the CS groups were either challenged with cold stress at 18°C (+ CS group) or maintained at a temperature of 26°C during the feeding period (- CS group). The results showed that CS challenge significantly (p < 0.05) impaired the growth indices, redox status, and immune response in the challenged fish compared to the non-challenged fish. On contradictory, the inclusion of PR into fish diets enhanced (p < 0.05) the feed intake, growth indices, antioxidant enzyme activity, and immunological parameters. Moreover, PR treatment alleviated the CS deterioration of fish weights, specific growth rates, feed efficiency, antioxidant enzyme activity, lymphocyte proliferation, and phagocytosis activity and alleviated the elevated mortality, H/L ratio, and malondialdehyde levels by cold stress. It is concluded that the inclusion of propolis at 10 g/kg in the diet of Nile tilapia fish could be approved as a nutritional approach to enhance their performance, especially when stressed by low-temperature conditions.

Understanding Relationship between Length and Weight with Otolith Dimension of &lt;i&gt;Tenualosa ilisha&lt;/i&gt; from Hooghly River (India)&lt;sup&gt;1&lt;/sup&gt;

The Indian hilsa shad, Tenualosa ilisha (Hamilton, 1822), is a highly valued fish of the Indo Pacific region. This paper represents the length-weight relationships (LWR), condition factor (K), relative condition factor (Kn), and otolith dimension of hilsa, throughout the Hooghly River (West Bengal) from January to December 2020. The value of exponent “b” in the equation W = cLb was 2.6 for the species. It suggests the growth rate almost follows the cube law. Most of the population under study complied with the ideal b-value. Regression analysis indicated a high positive correlation between length and weight in the species (R2 = 0.76). The Kn shows their general well-being to be good in the river. The relationships between total fish weight and otolith biometry parameters such as long arm (L.A) length, short arm (S.A) length, L.A/S.A, and diameter (D) were examined. Linear regressions have represented fish weight-otolith biometry relationships. Regression analysis indicated a strong positive relationship between body weight and otolith length (R2 = 0.848), otolith diameter (R2 = 0.803), and short arm length of otolith (R2 = 0.678), but no relationship was found between L.A/S.A of otolith and fish weight. This strong relationship between fish weight and otolith length and diameter of T. ilisha, reflects that otolith length and diameter could become the best predictor of fish weight.

Specific Growth Rate (SGR) in Different Stages of Tilapia (Oreochromis niloticus) Production Cycle in Cemented Tank Based Semi-Intensive Aquaculture System

Traditional assessment of specific growth rate (SGR) using the data of the beginning and the end of aquaculture production cycle, avoiding intermediary data, is criticized as misleading way by the scholars. However, by knowing SGR in different stages of fish growth, the utilization of feed by fish can be well known. The study was conducted with aim to assess SGR of Tilapia in six concrete tanks for 90 days from 8th May to 10th August, 2017. Tilapia (Oreochromis niloticus) fry was released at the rate of 4 fry per tank equivalent to the stocking density of 160 fishes/decimal as of the semi-intensive aquaculture system. Sinking and floating feeds were used for feeding the fish in T1 and T2, respectively with three replications for each treatment. During the experimental period, feed was given at the rate of 20%, 15% and 10% of the body weight in 1st, 2nd and 3rd month, respectively. Moreover, aeration facilities were installed for 24 hours using air stone aerator. The weight of fish was recorded using digital balance in 3 days interval to measure SGR. The water quality parameters i.e., temperature and dissolved oxygen (DO) were recorded twice daily. The weight gains of fish were 49.90±2.40 g and 63.12±4.97g for T1 and T2, respectively. The mean percent weight gain of Tilapia was higher in T2 (747±0.00 g) than T1 (253.51±0.00 g). Feed conversion ratio (FCR) in T1 and T2 were 1.70±0.07 and 2.53±0.20, respectively. Considering the data at the beginning and the end of the production cycle, the SGR (% per day) of Tilapia in T1 and T2 were 6.27±3.27 and 6.26±3.83, respectively. The SGR for floating feed was higher at the initial stage of production cycle and lower in the later stages. For sinking feed, SGR was almost static from the beginning to the end. The higher FCR in T2 correlated with the lower SGR in the later stage of the culture period. This confirmed that farmers using floating feed with pre-determined amount of feeding ration, waste the expensive feed and money. Higher total production was obtained in T2 (830.96 g) than T1 (610 g) with 100% survival in both treatments. Therefore, determining SGR in a specific interval, at least 15 days interval, might be the efficient feeding practice of Tilapia farmers.

Potential role of dietary zinc on gene regulation of growth performance and immunity in Pangasianodon hypophthalmus against multiple stresses

In recent times, pollution and climate change have increased the risk of climate penalties particularly in aquatic ecosystems. Rising the temperature, metal pollution and ammonia contaminant are interlinked and have impact on aquatic life. This study investigates dietary zinc (Zn) for mitigation of arsenic, ammonia and high temperature stress on Pangasianodon hypophthalmus. The fish were exposed to different combination of arsenic (2.68 mg L−1), ammonia (NH3, 2.0 mg L−1) pollution and high temperature (34 °C) stress for 105 days. The average fish weight was 5.44 ± 0.17 g with length of 6.23 cm. The experiment involved 12 treatment groups, each with 18 fish in triplicates, totaling six hundred forty-eight fish (648). The treatments include control, As, NH3, As+NH3, NH3 + T, As+NH3 + T, Zn-5 mg kg−1, Zn-10 mg kg−1, Zn-15 mg kg−1, Zn-5 mg kg1As + NH3 + T, Zn-10 mg kg−1As + NH3 + T and Zn-15 mg kg−1As + NH3 + T. The gene related to apoptosis, cytokines, chemokines, immunity and growth particularly nuclear factor kappa B (NFkB), were studied in liver and gill tissues. Diets containing zinc were prepared with graded levels of 0, 5, 10 and 15 mg kg−1 diet. Cortisol, inducible nitric oxide synthase (iNOS), heat shock protein (HSP70), and metallothionine (MT), catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx), were upregulated by arsenic (As), ammonia (NH3) and high temperature (34 °C) stress, but downregulated with dietary Zn at 10 mg kg−1 diet. The NFkB pathway genes, including caspase 3a (CAS 3a), tumour necrosis factor (TNFα), interleukin (IL), and toll-like receptors (TLR), were noticeably upregulated due to stressors. However, Zn supplementation downregulated these genes and mitigated stress in the fish exposed to As+NH3 + T. Genes related to growth hormone (GH), growth hormone regulator 1 and β (GHR1 and GHRβ), were noticeably downregulated in response to stressors. Conversely, Zn-containing diets significantly upregulated GH, GHR1, and GHRβ, while myostatin (MYST) and somatostatin (SMT) results differed from other growth-related genes. The liver and kidney tissues showed the highest arsenic bioaccumulation. Notably, Zn-containing diet was observed to protect fish from Aeromonas hydrophila infection. Overall, the results indicate that Zn-containing diet at 10 mg kg−1 diet improved the regulation of the stress-related genes, enhancing the mitigating ability of fish against multiple stressors.

Effects of dietary hydrolysate supplementation on growth, body composition, hematological responses, and liver histology of juvenile giant trevally (Caranx ignobilis Forsskal, 1775).

A feeding study was conducted to investigate how fish protein hydrolysate (FPH) supplementation affected the growth, feed utilization, body composition, and hematology of juvenile giant trevally (Caranx ignobilis Forsskal, 1775). Seven isonitrogenous (52% protein) and isocaloric diets (10% lipid) were formulated, wherein shrimp hydrolysate (SH) and tuna hydrolysate (TH) were used to replace fishmeal at inclusion levels of 0 (control), 30, 60, and 90 g/kg and labeled as control, SH30, SH60, SH90, TH30, TH60, and TH90, respectively. Each diet was fed to triplicate groups of juvenile giant trevally for 8 weeks. The results showed higher final body weight and specific growth rate in fish fed SH30, SH60, TH30, and TH60 than fed control diet. No difference was observed in feed intake, but reduced feed conversion ratio (FCR) was found in fish fed SH30, SH60, TH30, and TH60, demonstrating these diets improved feed utilization. TH90 caused deposition of lipid droplet in the hepatocyte, a sign of liver damage. Total monounsaturated fatty acids, polyunsaturated fatty acids (PUFA), and highly unsaturated fatty acids in fish were not affected by FPH supplementation. Fish fed TH30 showed lower ∑n - 3 PUFA than the fish fed remaining dietary treatments. The elevated serum protein was seen in fish fed control, SH30, SH60, and TH30, demonstrating that these diets were beneficial for the innate immune response in giant trevally. The results indicate that TH and SH could be incorporated into diets of giant trevally at 30-60 g/kg, replacing 7%-13% fishmeal with enhanced growth and health benefits.

Performance, processing yields, and fillet composition of specific United States diploid and triploid rainbow trout (Oncorhynchus mykiss) lines reared in a semi-commercial scale freshwater recirculating aquaculture system

Large rainbow trout marketed as steelhead are gaining considerable attention for production in recirculating aquaculture systems (RAS). Diploid and triploid trout with varying genetics are available from several commercial suppliers; however, the performance and processing metrics of these lines have not been compared when raised in freshwater RAS. Current data on these outcomes could support more accurate cost and profitability estimates for potential RAS projects and optimize operation for existing farms. Accordingly, the objective of this study was to quantify performance metrics, processing yield, and fillet composition of six all-female rainbow trout lines (three diploid and three triploid) exposed to an artificial winter (12:12 light: dark at 40 g (Artificial Winter Photoperiod; AWP)) or continuous, 24-h light (No Winter Photoperiod; NWP) grown in a semi-commercial scale freshwater RAS to 3.5 kg. Overall, growth was impacted by line, ploidy, and artificial winter photoperiod. Diploid and AWP trout were smaller than triploids and NWP trout at stocking and 500 g. Mean diploid and triploid weight was similar at larger sizes (>1 kg); however, triploid performance compared to diploids varied by commercial supplier. Mortality was lower in lines from commercial supplier 1 than lines from commercial supplier 2 and the United States Department of Agriculture (14.4 ± 0.8 vs 27.5 ± 2.0 and 29.8 ± 4.3%, respectively). Head-on gutted and skin-on fillet yields were related with larger fish weight. Mature prevalence in diploids may have led to differences observed between diploids and triploids in fillet lipid (10.9 ± 0.8 vs 13.3 ± 0.6%) and moisture (67.0 ± 0.6 vs 65.1 ± 0.4%). The results provide guidance for rainbow trout RAS producers to make informed decisions on optimal harvest size targets and tailor their rainbow trout line or ploidy selection to those harvest sizes.

An integrated approach for evaluating freshwater ecosystems under the influence of high salinity: a case study of Manchar Lake in Pakistan.

Manchar Lake, Pakistan's biggest lake in the arid zone, faces human-induced salinity issues. This study investigated its effects on the multifaceted ecosystem services, including serving as a source of drinking and irrigation water and aquatic health through assessing fish diversity and characteristics. Analyses of 189 water samples from 21 sites revealed spatiotemporal variations in major ions contributing to lake water salinity. The study assessed water suitability for drinking and agriculture using the water quality index (WQI), sodium adsorption ratio (SAR), magnesium hazard (MH), sodium percent (Na%), and Kelly's ratio (KR). The WQI, ranging from 141 to 408, indicated that the lake water was unfit for drinking. In some seasons, such as the pre-monsoon period, the lake water was deemed unsuitable for irrigation due to high SAR values (18 ± 4 g/L, average ± standard deviation), consistently rising MH values exceeding 66 in all seasons and elevated sodium percentages surpassing 66% in both the pre-monsoon and monsoon seasons. The KR remained acceptable (averaging 0.8 to 2.5) in all seasons. Fish health in highly saline conditions was assessed using data from interviews, focus group discussions, and fish sampling (1684 fish from 10 sites). Results depicted that high salt contamination severely impacted fish length and weight. The study found low richness (Simpson's biodiversity: 0.697 and Shannon Weaver: 1.51) and evenness (Pielou's index: 0.48) among the fish populations. Since 1998, Manchar Lake has seen a decline in fish varieties from 32 to 23, with changes in fish species' feeding habits. To improve lake water quality, the study recommends diverting saline water to the sea before and after the monsoon season while utilizing freshwater from alternative sources to fill any water deficit.

LENGTH-WEIGHT RELATIONSHIP OF EIGHT SPECIES OF FISH CAUGHT BY TRADITIONAL PAPUAN FISHERS IN YOUTEFA BAY, INDONESIA

In this study, data on length and weight of fish were used to determine the length-weight relationship and condition factors of eight fish species that are targeted by traditional Papuan fishers and have high economic value (Lutjanus fulvus, Gerres oyena, Parupeneus barberinus, Siganus spinus, Siganus canaliculatus, Pelates quadrilineatus. Mugil cephalus, and Hemiramphus far) in Youtefa Bay, Papua Province, Indonesia. A total of 245 fish specimens were collected from Papuan fishermen during the period January to March 2020. The total length and body-weight of the fish specimens studied ranged from 15.2 to 32.1 cm (average 20.26±3.73 cm) and 42.72 to 371.86 g (average 124.10±52.45 g), respectively. The b value ​​for all fish species studied ranged from 2.6919 to 3.0791, with the coefficient of determination (R2) ranging from 0.9022 to 0.9947. The growth patterns of the eight fish species were allometric (b ≠ 3; t-test &lt; t-tab), where L. fulvus (2.824), P. barberinus (2.9136), S. canaliculatus (2.989), P. quadrilineatus (2.9577), M. cephalus (2.9096), and H. far (2.6919) were negative allometric (b &lt; 3), while G. oyena (3.0596) and S. spinus (3.0791) are positive allometric (b &gt; 3). Meanwhile, the relative condition factor and Fulton condition factor values ​​ranged from 0.874 to 1.201 (average 0.999±0.321) and 0.204 to 2.726 (average 1.612±0.515). M. cephalus had a higher relative condition factor, while L. fulvus had a higher Fulton condition factor than other fish species

Effects of stocking density and water flow rate on performance, water quality and economic benefits of African catfish larvae (Clarias gariepinus Burchell, 1822) in the aquaponic system integrated with Azolla fern

The effect of stocking on fish performance is known is most systems, and for many fish. Meanwhile water flow rate remains an important factor in recirculating aquaculture systems. However less information is still available on the influence of aquaculture management practices on the performance of aquaponics. This study determined the effect of stocking density and water flow rate on growth performance of African catfish larvae (Clarias gariepinus) and Azolla spp. in catfish-Azolla aquaponics system. The 4 × 4 factorial experiment consisted of four larval stocking densities (1500 larvae/m3, 3000 larvae/m3, 4500 larvae/m3 and 6000 larvae/m3) and four water flow rates (0.25 L/min, 0.5 L/min, 0.75 L/min and 1 L/min) executed in triplicate. The stocking density and water flow rate had an interactive influence (P < 0.05) on the concentration of DO, TAN, and NO3−. The stocking density and water flow rate had an interactive influence (P < 0.05) on the final mean weight, SGR, and survival of C. gariepinus larvae, but not for FCR and yield (P > 0.05). The highest fish weight was achieved under combination of stocking density 3245 larvae/m3 and water flow rate of 0.87 L/min, but growth will still be optimized upto a stocking density of 4850 larvae/m3 but at higher combinations of water flow rates (> 0.875 L/min). The stocking density and water flow rate had an interactive influence (P < 0.05) on chlorophyll a concentration, but not fresh weight, dry weight and yield (P > 0.05). Enterprise budgets for aquaponic with different stocking densities and water flow rate for fish and Azolla production allowed all the treatments to post positive returns to risk and were viable investments. Cash flow projections were made over a 10 year period for each of the units with the net present value (NPV) and internal rate of return (IRR) revealed that sales of larval fish and Azolla sp. at stocking density of 1500 larvae/m3 were not profitable. However, all the other stocking densities were profitable except at 3000 larvae/m3 and water flow rate of 0.25 L/min. Although at all stocking density the revenue were able to cover the variable costs, this study recommends stocking at 3000 to 4500 larvae/m3 and water flow rate of 0.75 L/min and 1.00 L/min.

The effectiveness of ichthyochoric dispersal in forested wetlands of the Amazon depends on the species of fish and its size

The interaction between fish and plants in Amazon floodplain is fundamental for the maintenance of frugivorous fish and tree communities. The viability of seeds after passing through the digestive tract of fish is a central factor for seed dispersal since it can influence colonization and regeneration of these environments. Our study investigated the seed dispersal by frugivorous fish in a flooded forest in the Central Amazon. We also evaluated the seed germination speed after passage of the digestive tract of fish and how the size of fish and the seeds can influence the dispersion of tree seeds in floodplains. A total of 5,012 seeds from 49 plant species were found in the digestive tracts of 11 frugivorous fish species. The length and weight of the frugivorous fish were positively related to the size of seeds in the digestive tract. The germination of the seeds removed from the fish varied between species. The passage of the seeds of the different plant species through the digestive tracts of the fish did not significantly increase the germination speed. Considering the anthropogenic pressures present in these environments, we can expect that a reduction in body size for some species of fish, due to overexploitation, may have negative consequences for some tree species that are dispersed mainly via ichthyochory.

Towards an improved internet of things sensors data quality for a smart aquaponics system yield prediction

The mobile aquaponics system is a sustainable integrated aquaculture-crop production system in which wastewater from fish ponds are utilized in crop production, filtered, and returned for aquaculture uses. This process ensures the optimization of water and nutrients as well as the simultaneous production of fish and crops in portable homestead models. The Lack of datasets and documentations on monitoring growth parameters in Sub-Saharan Africa hamper the effective management and prediction of yields. Water quality impacts the fish growth rate, feed consumption, and general well-being irrespective of the system. This research presents an improvement on the IoT water quality sensor system earlier developed in a previous study in carried out in conjunction with two local catfish farmers. The improved system produced datasets that when trained using several machine learning algorithms achieved a test RMSE score of 0.6140 against 1.0128 from the old system for fish length prediction using Decision Tree Regressor. Further testing with the XGBoost Regressor achieved a test RMSE score of 7.0192 for fish weight prediction from the initial IoT dataset and 0.7793 from the improved IoT dataset. Both systems achieved a prediction accuracy of 99%. These evaluations clearly show that the improved system outperformed the initial one.•The discovery and use of improved IoT pond water quality sensors.•Development of machine learning models to evaluate the methods.•Testing of the datasets from the two methods using the machine learning models.

Optimizing XGBoost Performance for Fish Weight Prediction through Parameter Pre-Selection

Fish play a major role in the human nutritional system, and farmers need to know the accurate prediction of fish weight in order to optimize the production process and reduce costs. However, existing prediction methods are not efficient. The formulas for calculating fish weight are generally designed for a single species of fish or for species of a similar shape. In this paper, a new hybrid method called SFI-XGBoost is proposed. It combines the VIF (variance inflation factor), PCC (Pearson’s correlation coefficient), and XGBoost methods, and it covers different fish species. By applying GridSearchCV validation, normalization, augmentation, and encoding techniques, the obtained results show that SFI-XGBoost is more efficient than simple XGBoost. The model generated by our approach is more generalized, achieving accurate results with a wide variety of species. Using the r2_score evaluation metric, SFI-XGBoost achieves an accuracy rate of 99.94%.