Fish Body Research Articles

A Study of Age, Sex Ratio, Gonado-Somatic Index, Fecundity, and Breeding Season, of Nile Tilapia (Oreochromis niloticus Linnaeus, 1758) from Khashm El-Girba Reservoir and Atbara River, Eastern Sudan

This study aims to investigate some reproductive aspects of Nile tilapia, Oreochromis niloticus in the Khashm El-Girba reservoir and Atbara River, eastern Sudan. The study was conducted during December 2015 to November 2016. Samples were collected bi-monthly basis from three localities, namely; Um Aswad (Atbara River), El-Remila, and El-Monaba (Khashm El-Girba reservoir), using beach seine nets of 1.2 cm 4.0 cm and 7.0 cm stretched mesh. A total of 1595 O. niloticus specimens were collected from all sampling sites. The age of O. niloticus was estimated using five anterior vertebrae of fish body; The results indicate that the age ranged between 0+ to 4+ years. Most of the collected fish specimens were of age 1+, with females most dominant at this age. Sex ratio was 1:1(M: F). Gonado-somatic index (GSI) of females of O. niloticus ranged between 1.965 – 2.620, and from 0.434 – 0.439 for males. Two periods of increase of GSI were observed reflecting two breeding seasons of this species. Used gravimetric method to estimate the average fecundity of O. niloticus ranged between 481 eggs in Um Aswad sampling site, and 638 in El-Remila site. The fecundity of O. niloticus has a high correlation with gonadal weight (r=0.82708) but a low correlation with standard length (r=0.47612) and total weight (r=0.50874). The results of this investigation on O. niloticus indicate that the age of the fish ranged from 0+ to 4+ years, with a sex ratio of 1:1. The Gonado-somatic Index (GSI) indicated two spawning seasons, and fecundity was found to be strongly correlated with gonad weight, and moderately correlated with total length and standard length. This results can be used formulate management policies and procedures for protecting and conserving the fisheries resources and to regulate and improve the catches of the most important commercial fish species in that region.

Gastrotomy for removal of a gastric fishhook foreign body in a blue catfish (Ictalurus furcatus)

AbstractAn adult blue catfish (Ictalurus furcatus) presented for ingestion of a fishing lure. Manual retrieval of the fishing lure was attempted via palpation of the stomach through the oral cavity and oesophagus. The lure was palpable within the lumen of the stomach, but it could not be safely extracted, as one of the treble‐barb hooks on the lure had perforated the gastric wall. The lure was surgically removed via gastrotomy. Six weeks following surgery, the patient experienced dehiscence of the skin incision, which was left open for healing by second intention. The patient made a complete recovery. This is the first documented gastrotomy for successful removal of a gastric fishhook foreign body in a teleost fish.

Biofiltering capacity of Chambardia rubens (Bivalvia: Unionidae) may modulate expression of stress and growth genes inhibited by the neonicotinoid insecticide acetamiprid in zebrafish

Neonicotinoid insecticides specifically target insect subtypes of nicotinic acetylcholine receptors. Acetamiprid (ACE: C10H11ClN4), the neonicotinoid insecticide, is used to control crop insect pests worldwide. It is a nitrile, monochloropyridine, and carboxamidine that is highly soluble and accessible to waterways. There, it causes neurotoxic and oxidative perturbance to non-target organisms. The unionid mussel Chamabradia rubens is a common Northern River Nile suspension feeder. The current study aimed to assess ACE filtration from waters by C. rubens, and whether this biological power can reduce ACE effects on fish. Removal of ACE by C. rubens was assessed using LC-MS/MS. Zebrafish Danio rerio adults were exposed to different sublethal doses of ACE in the presence or absence of C. rubens in their aquaria. The results showed that mussels could remove significant ACE amounts from water, where it accumulated mostly in the digestive gland. The presence of C.rubens in zebrafish aquaria having ACE was accompanied by significant upregulation of antioxidant enzyme gene transcripts and total H2O2 scavenging, in contrast to mussel-free ACE-exposed groups. Meanwhile, liver triglycerides rose 5-6-fold in response to ACE in the “Fish-Only” groups, indicating an ACE-induced hepatotoxicity. Also, Insulin-like growth factor 1 (igf1) and fish body mass increased more in “Fish + Mussel” groups than in the “Fish-Only” ones. In aggregate, these findings suggest that the Nile mussel could reduce the oxidative stress and metabolic changes induced in fish by ACE. This can contribute valuable environmental and economic benefits upon the use of this mussel as a biofilter.

Zoonotic human liver flukes, a type 1 biocarcinogen, in freshwater fishes: genetic analysis and confirmation of molluscan vectors and reservoir hosts in Bangladesh

BackgroundOpisthorchiid flukes, particularly Opisthorchis viverrini, Opisthorchis felineus, Clonorchis sinensis, and Metorchis spp. are the most common fish-borne zoonotic human liver flukes (hLFs). Liver fluke infections are more prevalent in resource-deprived and underprivileged areas. We herein estimated the prevalence of the metacercariae (MC) of major hLFs in common large freshwater fishes (lFWF) marketed for human consumption from some selected areas of Bangladesh along with detection of their molluscan vectors and reservoirs.MethodsThe current status of fish-borne zoonotic hLF infections in lFWF was investigated along with their molluscan vectors and mammalian reservoir hosts in Mymensingh and Kishoreganj in Bangladesh from July 2018–June 2022 using conventional and multiple molecular techniques, such as PCR, PCR-restriction fragment length polymorphism (RFLP), sequencing, and bioinformatic analyses. The infection rate of fishes was analyzed using the Z-test and the loads of MC were compared using the chi-squared (χ2) test.ResultsThe MC of C. sinensis, Opisthorchis spp., and Metorchis spp. were detected in 11 species of common and popular lFWF. In lFWF, the estimated prevalence was 18.7% and the mean load was 137.4 ± 149.8 MC per 100 g of fish. The prevalence was the highest (P < 0.05) in spotted snakehead fishes (Channa punctata, 63.6%). The highest rate of infection (P < 0.05) was observed with the MC of C. sinensis (11.8%). Metacercariae were almost equally (P > 0.05) distributed between the head and body of fishes. The infection rate was slightly higher in cultured (19.6%) fishes. The MC of C. sinensis, O. felineus, O. viverrini, and Metorchis orientalis in fishes were confirmed using PCR, PCR-RFLP and bioinformatics. The cercariae of opisthorchiid (Pleurolophocercus cercariae) flukes were only recovered from Bithynia spp. (3.9%, 42 out of 1089). The ova of hLFs from dogs (4.3%, 5 out of 116) and cats (6.0%, 6 out of 100), and adult flukes (M. orientalis) from ducks (41.1% 113 out of 275) were detected.ConclusionsThe MC of hLFs are highly prevalent in fresh water fishes in Bangladesh. Reservoir hosts, such as street dogs, cats, and ducks carried the patent infection, and residents of Bangladesh are at risk.Graphical

Research on Measuring the Bodies of Underwater Fish with Inclined Positions Using the YOLOv8 Model and a Line-Laser System

Fish body measurement is essential for monitoring fish farming and evaluating growth. Non-destructive underwater measurements play a significant role in aquaculture management. This study involved annotating images of fish in aquaculture settings and utilized a line laser for underwater distance calibration and fish body inclined-angle calculation. The YOLOv8 model was employed for fish identification and key-point detection, enabling the determination of actual body dimensions through a mathematical model. The results show a root-mean-square error of 6.8 pixels for underwater distance calibration using the line laser. The pre-training YOLOv8-n, with its lower parameter counts and higher MAP values, proved more effective for fish identification and key-point detection, considering speed and accuracy. Average body length measurements within 1.5 m of the camera showed a minor deviation of 2.46% compared to manual measurements. The average relative errors for body length and width were 2.46% and 5.11%, respectively, with corresponding average absolute errors. This study introduces innovative techniques for fish body measurement in aquaculture, promoting the digitization and informatization of aquaculture processes.

IMPROVE SPAWNING QUALITY OF KISSING GOURAMI (HELOSTOMA TEMMINCKII) WITH COMMERCIAL FEED CONTAINING GLUTATHIONE AND VITAMIN E

This research is needed to accelerate spawning by adding glutathione and vitamin E in the feed to produce quality fish seeds. The aim is to determine the effect of adding vitamin E to commercial feed containing glutathione on increasing gouramy spawning. All treatment was carried out for two months using a Completely Randomised Design (CRD) with 4 treatments and 3 replications. Treatment A (glutathione), B (glutathione and vitamin E 150 mg.kg–1), C (glutathione and vitamin E 300 mg.kg–1), and D (glutathione and vitamin E 450 mg.kg–1). 12 broodstock with male:female ratio of 1:1, weight range of 90-130 g obtained from nature. They fed as much as 5% of the fish body weight thrice daily. The results showed that the highest hatching rate was 99.67% in treatment D. The egg diameter in treatment C showed the best results (0.88 mm). The highest fecundity was 21.257 g in treatment D. The highest survival was 95.56% in treatment D. All feed treatments with a combination of glutathione and vitamin E gave a better response than the addition of glutathione alone. Polynomial regression analysis of the egg diameter parameter showed that the optimal dose of vitamin E was 282 mg.kg–1.

Thermal transfer rate is slower in bigger fish: How does body size affect response time of small, implantable temperature recording tags?

AbstractThe recent miniaturisation of implantable temperature recording tags has made measuring the water temperatures fish experience in the wild possible, but there may be a body size‐dependent delay in implanted tag response time to changes in external temperature. To determine whether fish body size affects the response rate of implanted temperature tags, we implanted 20 Salvelinus fontinalis (127–228 mm fork length (FL), 15.1–120.4 g) with temperature recording tags and subjected them to rapid temperature changes (±8°C in less than 2 seconds) in the laboratory. We found that thermal transfer rates, and the lag in temperature tag response rate, was positively correlated with fish size, but the direction of temperature change (colder or warmer) had no significant effect. In fish exposed to a slower rate of temperature change (2°C h−1) implanted tags did not show a response lag. Understanding the limitations of this important technology is crucial to determining the utility of the data it produces and its ability to accurately measure fish thermal experience in the wild.

DyFish-DETR: Underwater Fish Image Recognition Based on Detection Transformer

Due to the complexity of underwater environments and the lack of training samples, the application of target detection algorithms to the underwater environment has yet to provide satisfactory results. It is crucial to design specialized underwater target recognition algorithms for different underwater tasks. In order to achieve this goal, we created a dataset of freshwater fish captured from multiple angles and lighting conditions, aiming to improve underwater target detection of freshwater fish in natural environments. We propose a method suitable for underwater target detection, called DyFish-DETR (Dynamic Fish Detection with Transformers). In DyFish-DETR, we propose a DyFishNet (Dynamic Fish Net) to better extract fish body texture features. A Slim Hybrid Encoder is designed to fuse fish body feature information. The results of ablation experiments show that DyFishNet can effectively improve the mean Average Precision (mAP) of model detection. The Slim Hybrid Encoder can effectively improve Frame Per Second (FPS). Both DyFishNet and the Slim Hybrid Encoder can reduce model parameters and Floating Point Operations (FLOPs). In our proposed freshwater fish dataset, DyFish-DETR achieved a mAP of 96.6%. The benchmarking experimental results show that the Average Precision (AP) and Average Recall (AR) of DyFish-DETR are higher than several state-of-the-art methods. Additionally, DyFish-DETR, respectively, achieved 99%, 98.8%, and 83.2% mAP in other underwater datasets.

The Prevalence of Marine Lipophilic Phycotoxins Causes Potential Risks in a Tropical Small Island Developing State.

Tropical small island developing states (SIDS), with their geographical isolation and limited resources, heavily rely on the fisheries industry for food and revenue. The presence of marine lipophilic phycotoxins (MLPs) poses risks to their economy and human health. To understand the contamination status and potential risks, the Republic of Kiribati was selected as the representative tropical SIDS and 55 species of 256 coral reef fish encompassing multiple trophic levels and feeding strategies were collected to analyze 17 typical MLPs. Our results showed that the potential risks of ciguatoxins were the highest and approximately 62% of fish species may pose risks for consumers. Biomagnification of ciguatoxins was observed in the food web with a trophic magnification factor of 2.90. Brevetoxin-3, okadaic acid, and dinophysistoxin-1 and -2 were first reported, but the risks posed by okadaic acid and dinophysistoxins were found to be negligible. The correlation analysis revealed that fish body size and trophic position are unreliable metrics to indicate the associated risks and prevent the consumption of contaminated fish. The potential risks of MLPs in Kiribati are of concern, and our findings can serve as valuable inputs for developing food safety policies and fisheries management strategies specific to tropical SIDS contexts.

Evaluation of Himalayan nettle (Urtica ardens) extract meal in common carp (Cyprinus carpio) feed: Impact on growth performance, digestive enzyme activity and antioxidant capacity

This research aims to evaluate the impact of an extract derived from the leaves of Himalayan nettle (Urtica ardens) leaf extract on common carp, Cyprinus carpio, growth, digestive enzymes, fish body carcass composition, antioxidant system, and water quality parameters. For a duration of 90 days, experimental diets containing nettle extract were given to 150 fish (12.38 ± 0.53 g) in 15 tanks (10 fish per tank). The five groups in triplicate were: control or T0 (untreated), T1 (fed 0.3% extract), T2 (0.6% extract), T3 (0.9% extract), and T4 (1.2% extract). Results revealed that nettle extract in the diet increases common carp growth up to 0.9% concentration of extract. Its feed conversion ratio decreases, while weight gain and specific growth rate rise significantly compared to the control diet. No mortality was observed during the 90-day experiment. Dietary nettle extract did not affect whole-body fibre and crude ash percentages (p > 0.05). Nettle-fed and control groups showed significant differences in crude protein, body fat, and total body moisture (p < 0.05). After a 90-day feeding trial, 0.9% nettle extract-fed fish had higher protease, amylase, lipase, and cellulase levels than the control group (p < 0.05). When nettle content reached 1.2%, enzyme activity decreased. Orthophosphate production peaked at 4 and 8 hours after feeding, while ammonia excretion peaked at 2 and 6 hours. The control group excreted the most ammonia and orthophosphate, while the 0.9% group excreted the least. Liver and kidney SOD levels were higher in common carp fed a 0.6% nettle extract diet. Feeding with a 0.9% nettle extract diet improved hepatic lipid peroxidation, gut and liver glutathione. Gut and kidney SOD, catalase, LPO, and GSH increased dramatically on the 1.2% diet. Statistically, the 0.9% nettle extract (T3) group showed the overall best results compared to the control diet. These findings demonstrate the potential of nettle extract as a dietary supplement in aquaculture.

Assessment of body metrics, weight, and carcass yields in dusky grouper (Epinephelus marginatus) through correlation and path analysis: Implications for optimizing genetic breeding programs

One of the objectives of aquaculture selective breeding programs is to enhance body conformation traits, often by using indirect criteria like correlation between live body measurements and carcass traits. This research investigated the relationship between live body measurements and carcass traits in dusky grouper (Epinephelus marginatus). We assessed the relationship between body measurements and carcass traits in 150 farmed dusky groupers with an average weight of 680 ± 221 g. The fish were measured for length, width, height, and length of head, and then processed to obtain weights (body, fillet, steaks, head, and residues) and yields (carcass, fillet, steaks, head, and residues). Path analysis was employed to estimate direct and indirect effects, with body part weight and yields as dependent variables and morphometric measurements and relationships as explanatory variables. The findings indicate that morphometric measurements can be used to estimate farmed dusky grouper body weights and carcass yields. Among the morphometric measurements and relationships examined, fish body height and standard length were identified as the main factors influencing variation in body weights and carcass yields.

Prolonged exposure to mercuric chloride induces oxidative stress-mediated nephrotoxicity in freshwater food fish Channa punctatus.

Mercury (Hg) is regarded as a serious hazard to aquatic life and is particularly prevalent in aquatic ecosystems. However, there is little evidence available regarding the toxicity of mercury chloride (HgCl2) in vital organs of fish. This study was conducted to assess the effects of HgCl2 (0.039mg/L and 0.078mg/L) on oxidative stress-mediated genotoxicity, poikilocytosis, apoptosis, and renal fibrosis after 15, 30, and 45days of the exposure period. According to the findings, HgCl2 intoxication in fish resulted in a significantly (P < 0.05) elevated lipid peroxidation (LPO), protein carbonyls (PC), lactate dehydrogenase (LDH) activity levels in kidney tissues and significantly (P < 0.05) increased reactive oxygen species (ROS), poikilocytosis, DNA tail length, and the frequency of apoptotic cells (AC%) in blood cells. Kidney's ultra-structure and histopathology revealed its fibrosis, which was evident by mRNA expression of targeted genes KIM1, NOX4, TGFβ, and NFϏβ. Different indicators of oxidative stress, apoptosis, and genotoxicity were altered in a dose and time-dependent manner, according to a two-way ANOVA analysis. There was a considerable positive link between oxidative stress and kidney fibrosis in the fish Channa punctatus, and it is evident from regression correlation and PCA data analysis. The kidney's ultra-structure evaluation and histopathology both revealed a noticeable fibrosis state. Additionally, a significant (P < 0.05) downregulation in PPARδ reveals that fish body was unable to combat diseases such as kidney fibrosis induced by HgCl2. This study shed fresh light on the mechanisms underlying nephrotoxicity caused by HgCl2 exposure.

Effect of Biologger Attachment on the Stress and Health State of the Spotted Sea Bass Lateolabrax maculatus

The biologger is a widely used tool in biotelemetry for investigating marine fish. However, studies reported that the attachment of biologgers has a negative effect on the target organisms. We assessed the health status of spotted sea bass with attached biologgers by analyzing changes in their serum biochemistry and biomarker gene expression at varying biologger/fish body weight ratios. Especially, the assessment of the health status using biomarker genes offers the rapid evaluation of the condition of an individual. The genes bax, hsp70-2, and Cx32.7, associated with apoptosis, stress, and immunity, were selected as biomarker genes to assess the fish stress levels and overall health. The experimental groups included a control group without the biologger (C) and biologger-equipped groups, each carrying a biologger whose weight was 2.0–3.0% (W2), 5.0–6.0% (W5), and 10.0–12.0% (W10) of the fish body weight. Blood samples were collected on days 0, 1, 7, 14, and 21 post-attachment. The expression of bax, hsp70-2, and Cx32.7 was analyzed in the liver and muscle on day 21. The W10 group showed significantly higher levels of superoxide dismutase on day 1 and of glutamic oxaloacetic transaminase and glutamic pyruvic transaminase on day 7 than the other groups. On day 21 post-attachment, regardless of the biologger/fish body weight ratio, the liver and muscle tissues from groups W2, W5, and W10 showed significantly higher expression of bax, hsp70-2, and Cx32.7 than those from group C, respectively. However, there was no significant change in blood parameters depending on the weight of the attached biologger on day 21 post-attachment. These results indicate that the spotted sea bass gradually adapted to the attached biologgers of weights up to 10–12% of their body weight under our experimental conditions, providing clues to determine the timing of biologger release for biotelemetry studies.

Non-Contact Tilapia Mass Estimation Method Based on Underwater Binocular Vision

The non-destructive measurement of fish is an important link in intelligent aquaculture, and realizing the accurate estimation of fish mass is the key to the stable operation of this link. Taking tilapia as the object, this study proposes an underwater tilapia mass estimation method, which can accurately estimate the mass of free-swimming tilapia under non-contact conditions. First, image enhancement is performed on the original image, and the depth image is obtained by correcting and stereo matching the enhanced image using binocular stereo vision technology. And the fish body is segmented by an SAM model. Then, the segmented fish body is labeled with key points, thus realizing the 3D reconstruction of tilapia. Five mass estimation models are established based on the relationship between the body length and the mass of tilapia, so as to realize the mass estimation of tilapia. The results showed that the average relative errors of the method models were 5.34%~7.25%. The coefficient of determination of the final tilapia mass estimation with manual measurement was 0.99, and the average relative error was 5.90%. The improvement over existing deep learning methods is about 1.54%. This study will provide key technical support for the non-destructive measurement of tilapia, which is of great significance to the information management of aquaculture, the assessment of fish growth condition, and baiting control.

High-latitude ocean habitats are a crucible of fish body shape diversification.

A decline in diversity from the equator to the poles is a common feature of Earth's biodiversity. Here, we examine body shape diversity in marine fishes across latitudes and explore the role of time and evolutionary rate in explaining the diversity gradient. Marine fishes' occupation of upper latitude environments has increased substantially over the last 80 million years. Fishes in the highest latitudes exhibit twice the rate of body shape evolution and one and a third times the disparity compared to equatorial latitudes. The faster evolution of body shape may be a response to increased ecological opportunity in polar and subpolar oceans due to (1) the evolution of antifreeze proteins allowing certain lineages to invade regions of cold water, (2) environmental disturbances driven by cyclical warming and cooling in high latitudes, and (3) rapid transitions across depth gradients. Our results add to growing evidence that evolutionary rates are often faster at temperate, not tropical, latitudes.

Identification of microplastics content in milkfish (Chanos chanos), water and sediment in ponds in Muncung Village, Kronjo District

Plastic is a product that is currently popular among people, but over time plastic can be dangerous for the environment. Plastic can degrade into smaller particles known as microplastics. Microplastics in waters can harm aquatic biota such as fish. The size of microplastics is so small that it easily enters the fish's body, settles in the digestive tract and affects the fish's life cycle. Apart from biota, microplastics also pollute water and sediment. The aim of this research is to determine the abundance of microplastics and identify the characteristics of microplastics in milkfish in ponds in Muncung Village. The method used is take fish from ponds at 6 stations along with water and sediment. The fish were dissected and the digestive organs and flesh were removed, while the water and sediment were treated with NaCl. The microplastics found will be tested by FTIR to determine the polymer. The results of the observations showed that there were 3 types of microplastics, namely fragments, fibers and films. The highest abundance in organs was in the intestine, while microplastics were also found in water and sediment. FTIR test results show 6 plastic polymers in milkfish, namely ABS, latex, PVC, PP, EVA and nitrile. Keywords: Microplastics, milkfish, FTIR, Muncung Village

An approach to optimizing dietary protein to growth and body composition in walking catfish, Clarias batrachus (Linneaeus, 1758).

Clarias batrachus is a commercially important food fish. In the present study, effect of varying dietary protein levels was evaluated on the survival, growth parameters and proximate composition of C. batrachus. Diets comprising 25%, 30%, 35%, 40%, 45%, and 50% crude protein (CP) were supplied to fish in T1, T2, T3, T4, T5, and T6, respectively, at the rate of 5% of fish body weight for the entire 90 days, twice daily. Size of each stocked C. batrachus was recorded after 15 days. Results revealed 100% survival rate of C. batrachus in all treatments. Significantly highest (P<0.001) mean value of weight gain (g/fish), percent weight gain, daily growth rate, specific growth rate and protein efficiency ratio (PER) in C. batrachus were recorded, reared in T4 by feeding 40% CP in diet. The best FCR value (1.90±0.02) for C. batrachus was obtained in T4 by feeding 40%CP in diet. Mean value of water, ash, fat and protein contents (wet mass) were ranged 74.10-79.23%, 3.12-4.68%, 3.90-4.43% and 13.09-16.79% for C. batrachus in the studied treatment groups. Water content (%) was found significantly (P<0.05) higher in the body of C. batrachus for T1, T2, T3 and T6 than for T4 and T5. Ash was found significantly (P<0.05) higher in the fish reared in T4 and T5. Fat content in the wet body mass of C. batrachus was found significantly higher in T4 and T1. While, significant higher (P<0.05) values of mean protein content was noted in C. batrachus reared in T4 and T5. Body composition of C. batrachus was also categorically affected by body size, however, condition factor showed non-significant correlation in most of the relationships in the present study. Overall, results indicated that feeding appropriate diet (containing 40% CP) to the fish resulted good growth performance, lower FCR and higher protein content in the fish. Present study provides valuable knowledge of optimal dietary protein level in C. batrachus which will help in commercial success of aquaculture.

Recuperative Effects of Cinnamon (Cinnamomum zeylanicum) in Catla catla After Sub-Lethal Exposure to Lead.

This research was conducted to validate the beneficial effects of incorporating dietary cinnamon (Cinnamomum zeylanicum) powder (CzP) in alleviating lead (Pb) poisoning in fish. Healthy Catla catla individuals (16.36 ± 0.19g/fish) were distributed across 18 tanks in triplicate groups. The experimental groups were as follows: Control group: fish without supplementation or exposure to Pb; positive control group: fish without supplementation but exposed to 1mg/L Pb; 5g/kg CzP along with 1mg/L Pb exposure; 10g/kg CzP along with 1mg/L Pb exposure; 15g/kg CzP along with 1mg/L Pb exposure; and 20g/kg CzP along with 1mg/L Pb exposure. The trial continued for a period of 60days. Waterborne Pb had a deleterious effect on fish growth performance, body composition, blood profile, and digestive enzyme activity, along with elevated Pb accumulation in various tissues. Conversely, consumption of cinnamon effectively mitigated the toxic potential of Pb and enhanced fish longevity. Notably, 10g/kg CzP boosted growth, improved carcass quality, reversed blood indices, restored enzyme function in the gut, and mitigated Pb accumulation in tissues. In summary, the findings revealed that incorporating 10g/kg of CzP as a dietary supplement in C. catla aquaculture could effectively counteract heavy metal toxicity.

Extractions: Data Infrastructures and the Public Good

This special issue invites reflection on digital forms of resource extractivism, through thinking-with microbes, fish, smart energy, and human bodies. We examine the confluence of infrastructure building, public good enactment, and nature datafication to account for novel forms of resource economies. The articles in this collection empirically investigate the various ways in which nature is turned into resource in laboratory and experimental sites including database retrievals and data mining. Our empirical cases, ranging from biodiversity prospecting, clinical biobanking to the digitalized electric grid and from digital fish to biodigital transformations in yeast technology, offer insights into the nexus of data, economy, nature, and information. Contributing to the literature on datafication of natural resources, these studies re-situate information infrastructures and biodigital extractions as part of emerging info-economies.

Development of novel fish-inspired robot with variable stiffness

In nature, real fish can adjust stiffness to improve their swimming speed and efficiency, which prompted us to apply the variable stiffness mode to a fish-inspired robot. In this paper, we adopt a mechanically adjustable compliance and controllable equilibrium position actuator (MACCEPA) to achieve a wide range of rotational stiffness change of the robotic fish body. Fish-inspired robots with offline/online variable stiffness mechanisms are developed. Then, swimming experiments are carried out to study the effect of the rotational stiffness of robot body on the swimming performance. Experimental data are processed using the undulatory reconfiguration technique. The offline variable stiffness fish-inspired robot achieved a maximum stride length of 0.7 BL/cycle (body length per cycle), which is basically equal to that of real fish. Experimental results revealed that in addition to the rotational stiffness of caudal fin, the rotational stiffness of fish body is also important and should increase with the driving frequency to achieve a better swimming performance. The rotational stiffness of fish body is the key factor for keeping the stride length stable, which offers a new insight for performance improvement of the high-frequency fish-inspired robot. The findings of this study are beneficial to the design of variable-stiffness fish-inspired robots.