Fish Feed Research Articles

Fish feeding rate affects the productive performance of whiteleg shrimp and lebranche mullet integrated culture using biofloc technology

Fish feeding rate affects the productive performance of whiteleg shrimp and lebranche mullet integrated culture using biofloc technology

Application of Cystoseira myrica phycosynthesized selenium nanoparticles incorporated with nano-chitosan to control aflatoxigenic fungi in fish feed.

The recurrent contaminations of feed materials with mycotoxigenic fungi can endanger both farmed animals and humans. Biosynthesized nanomaterials are assumingly the ideal agents to overcome fungal invasion in feed/foodstuffs, especially when utilizing sustainable sources for synthesis. Herein, the phycosynthesis of selenium nanoparticles (SeNPs) was targeted using Cystoseira myrica algal extract (CE), and the conjugation of CE/SeNPs with chitosan nanoparticles (NCt) to produce potential antifungal nanocomposites for controlling Aspergillus flavus isolates in fish feed. The phycosynthesis of SeNPs with CE was effectually carried out and validated using visible/UV analysis, X-ray diffraction and transmission microscopy; CE/SeNPs had diameters of 8.7 nm and spherical shapes. NCt/CE/SeNPs nanocomposite (173.3 nm mean diameter) was achieved and the component interactions were validated via infrared spectroscopic analysis. The antifungal assessment of screened nanomaterials against three Aspergillus flavus strains indicated that NCt/CE/SeNPs exceeded the fluconazole action using qualitative/quantitative assays. Severe alteration/distortions in A. flavus mycelial structure and morphology were microscopically observed within 48 h of NCt/CE/SeNPs treatment. The treatment of feed ingredients (crushed corn and feed powder) by blending with nanomaterials (NCt, CE/SeNPs and NCt/CE/SeNPs) led to significant reduction in A. flavus count/growth after storage for 7 days; NCt/CE/SeNPs could completely inhibit any fungal growth in feed material. The pioneering phycosynthesis of CE/SeNPs and their nanoconjugation with NCt generated bioactive antifungal agents to control A. flavus strains. The innovatively constructed NCt/CE/SeNPs nanocomposite is advised for application as an effectual, biosafe and natural fungicidal conjugate for the protection of fish feed from mycotoxigenic fungi. © 2024 Society of Chemical Industry.

БАЛЫҚ ДЕРНӘСІЛДЕРІН ӨСІРУ ҮШІН ОҢТАЙЛЫ ҚОРЕК РЕСУРСЫ РЕТІНДЕ АРТЕМИЯЛАРДЫ ӨНДІРУ

In aquaculture, the use of Artemia as an optimal nutrient resource for fish fry is an object of growing interest. The advantages of using Artemia include the possibility of mass cultivation under controlled conditions, the possibility of long-term storage in frozen form and resistance to external environmental conditions. Artemia, belonging to crustaceans, is a rich source of protein, fat, vitamins and minerals necessary for the healthy development of fish larvae. Due to the high content of unsaturated fatty acids, omega-3 and omega-6, fry contribute to the development of a healthy immune system, which reduces the risk of many diseases. Their small size and mobility make them available for cultivation, which ensures a high level of quality and reduces feed consumption. The results of the study show that the use of crustaceans as the main food source for fish farming contributes to improving the life, growth and health of fry. This makes them a successful type of feed in aquaculture and an optimal resource for fish farming. Further research in this area can lead to increased efficiency of fish farming, development of practices and improvement of the overall potential of the aquaculture industry. This article discusses the advantages of using Artemia, its biological value, ease of cultivation and versatility in the nutrition of various fish larvae. Various methods and technologies of growing Artemisia are analyzed, as well as their application in breeding species of fish larvae. Special attention is paid to optimizing the maximum growth of fish larvae and feeding conditions.

Effect of Scoparia dulcis Extract on Lipid Oxidation in Fish Feed, Growth Performance, and Hypoxia Tolerance in Juvenile Jian Carp (Cyprinus carpio var. Jian).

Lipid oxidation and hypoxia can lead to oxidative damage in aquatic animals. This study explored the effects of Scoparia dulcis extracts (SDE) on lipid oxidation, fish growth performance, digestive ability, antioxidant capacity, and hypoxia tolerance ability. The results showed that SDE decreased malonaldehyde (MDA), conjugated diene (CD), and peroxide value (PO) in the linoleic acid and linolenic acid as well as in fish feed. Broken-line analysis revealed that the optimal acetone extract of S. dulcis (AE) supplements was 4.02, 4.01, and 4.01 g kg-1 determined from PO, CD, and MDA, respectively. Dietary AE supplementation increased feed intake and specific growth rate and activities of amylase, trypsin, and lipase as well as alkaline phosphatase in fish hepatopancreas and gut. Polynomial regression analysis showed that optimal dietary AE supplement was 3.61 g kg-1 diet determined from weight gain. Furthermore, dietary AE supplementation decreased MDA content and increased glutathione content and the activities of glutathione peroxidase, catalase, superoxide dismutase, and glutathione reductase in fish digestive organs, gills, erythrocytes, and muscle. Dietary AE supplementation increased durative time (DT) and oxygen consumption rate (OCR) under hypoxia condition. Based on polynomial regression analysis, optimal dietary AE supplements were 4.73 and 4.60 g kg-1 diet determined from DT and OCR for hypoxia tolerance in fish, respectively. According to our current research, SDE's antioxidant capacity may be attribute to their phenolic chemicals.

A novel family of defensin-like peptides from Hermetia illucens with antibacterial properties.

The world faces a major infectious disease challenge. Interest in the discovery, design, or development of antimicrobial peptides (AMPs) as an alternative approach for the treatment of bacterial infections has increased. Insects are a good source of AMPs which are the main effector molecules of their innate immune system. Black Soldier Fly Larvae (BSFL) are being developed for large-scale rearing for food sustainability, waste reduction and as sustainable animal and fish feed. Bioinformatic studies have suggested that BSFL have the largest number of AMPs identified in insects. However, most AMPs identified in BSF have not yet undergone antimicrobial evaluation but are promising leads to treat critical infections. Jg7197.t1, Jg7902.t1 and Jg7904.t1 were expressed into the haemolymph of larvae following infection with Salmonella enterica serovar Typhimurium and were predicted to be AMPs using the computational tool ampir. The genes encoding these proteins were within 2 distinct clusters in chromosome 1 of the BSF genome. Following removal of signal peptides, predicted structures of the mature proteins were superimposed, highlighting a high degree of structural conservation. The 3 AMPs share primary sequences with proteins that contain a Kunitz-binding domain; characterised for inhibitory action against proteases, and antimicrobial activities. An in vitro antimicrobial screen indicated that heterologously expressed SUMO-Jg7197.t1 and SUMO-Jg7902.t1 did not show activity against 12 bacterial strains. While recombinant SUMO-Jg7904.t1 had antimicrobial activity against a range of Gram-negative and Gram-positive bacteria, including the serious pathogen Pseudomonas aeruginosa. We have cloned and purified putative AMPs from BSFL and performed initial in vitro experiments to evaluate their antimicrobial activity. In doing so, we have identified a putative novel defensin-like AMP, Jg7904.t1, encoded in a paralogous gene cluster, with antimicrobial activity against P. aeruginosa.

Development of an Efficient Fish Feed for Catla catla Post Larvae to Enhance the Survival Rates of Nursery Stages by Using Available Raw Materials

This study aimed to identify a new feed for Catla catla post larvae. There is no suitable feed in Sri Lanka for post-larvae of Indian carp. A complete randomized design was used. Two feeds were formulated using different nutrient compositions with 32 % and 25 % of the fish meal separately. The formulated feeds were used as treatment one and treatment two. Commercial feed was used as the control. Catla catla post-larvae were stocked at a density of 300 post larvae per m2 in nine cement tanks. Growth parameters were measured every two other days. Feeds were formulated according to the nutrient requirement of Catla catla post larvae. Water quality parameters were measured daily to maintain the water quality at the proper level. T-test preformed in Mini tab 16.0. Total body weight and length were significantly different (p<0.05). The survival percentage was higher in T1. Treatment feeds were not affected by the water quality parameters. Catla catla post-larvae show a maximum increase in length, survival percentage and weight in T1. It was concluded that T1 has a good combination of fish meal for Catla catla post-larvae. This study will help in future feed formulation for post-larvae feeds in developing nations.

Proximate Composition of Some Fish Feed Samples for Small-scale Aquaculture Farmers in Bobasi Sub-County, Kisii County, Kenya

Proximate Composition of Some Fish Feed Samples for Small-scale Aquaculture Farmers in Bobasi Sub-County, Kisii County, Kenya

Upgrading biogas plants to produce microbial proteins for aquaculture feed

As the world population continues to grow, alternative protein sources must be sought to meet increased protein needs and avoid the detrimental effects of traditional protein production. Microbial proteins (MP) are a low-carbon footprint alternative suitable for manufacturing food and feed. Bacterial-based MP can be produced at moderate costs using agro-waste, which is already utilised by anaerobic digestion (AD) plants to produce biogas and fertilisers. At present, there is the opportunity to turn existing AD plants into biorefineries for bio-based products like MP destined for fish feed. In this work, we evaluated the feasibility of biogas production coupled with MP production in the same medium-sized European biogas plant through mass and energy balances and basic economic assessment. The liquid phase rich in volatile fatty acids resulting from agro-waste fermentation was used to obtain MP by mixed cultures in a continuous stirred tank reactor, with the highest VSS productivity (1.21 g/L day) obtained at hydraulic retention times of 2–3 days. The obtained MPs were rich in proteins (74.0% of TVS), PHAs (22.5%) and essential amino acids, useable as feed ingredients in aquaculture. An initial economic analysis showed that the production of 590 tMP/year could yield a break-even price of 1300 €/t of MP, taking into account the investments in the new technology and additional operating costs. This analysis illustrates the competitiveness of a combined plant when evaluated against established market benchmarks and highlights a promising prospect for the expansion of MP production capacity.

AUTOMATION SYSTEM BASED ON ARDUINO ( Case Study in AQUAPONIC TOURISM VILLAGE )

Problems often faced by Perum Kandri residents regarding Aquaponics during the dry and rainy seasons. Residents still use tarpaulins to cover aquaponics manually, and feeding is still done manually. Aquaponic maintenance tools can be a solution for residents, to detect temperature and raindrops automatically, the author uses a DHT temperature sensor, raindrop sensor, RTC, mini servo, continuous servo and Arduino Uno R3 to design this maintenance tool. The tool that the author created can handle hot temperatures and during the rainy season, as well as feeding fish automatically , thereby reducing the possibility of the danger of death to vegetables and fish . The writer's tool can also close the roof automatically if it rains or hot during the day.

Design and Manufacturing of Solar Operated Automatic Fish Feeder System

One of the most significant aqua cultural endeavors to date is fish farming. Traditionally, the majority of fish feeding is done by hand, requiring the transportation of people to the feeding location. Fish feeding by hand requires more work, money, and time. Following an extensive survey of farmers across various regions regarding their approaches to fish farming, the Auto Switch Food Feeder, which utilizes new technologies to replace traditional farming methods, will automate farming practices. The design of the solar-powered fish feeder will be based on certain parameters, such as the capacity of the culture tank, stocking density, fish biomass, and feed diameter. Additionally, a user-friendly interface that is compact and convenient for farming will be designed. In the current project, user interface design and timing controls are applied to automate feeding methods, which will significantly save labor costs and efforts while improving the quality of fish feeding. Key Words: Fish Farming, Automatic feeding, automation etc.

Curcumin’s effects on growth indices, histological scores, blood metabolites, redox state, immunity, and antioxidant-related genes of red tilapia (Oreochromis sp.)

Curcumin, a polyphenol, targets multiple signaling molecules and shows activity at the cellular level, supporting its various health benefits. Thereafter, the present study examines the effects of different doses of dietary curcumin on growth indices, feed efficiency, serum metabolites, redox (oxidation) status, immunity, histological assessment, and antioxidant-related genes in red tilapia (Oreochromis sp, Oreochromis aureus x O. mossambicus). A total of 1200 red tilapia with an average weight of 19.1±0.03 g were distributed in 12 cement ponds (3×3.5×1m). Each treatment was assigned three pounds (n=100 replicates). For 60 days, fish were fed baseline diets containing 0, 0.4, 0.6, and 0.8 g of curcumin/kg of diet. The treated fish showed increased body weight and SGR (specific growth rate) compared to the T0 group (P<0.05). Curcumin in the diet significantly improved weight gain, percentages, and FCR (feed conversion ratio), with a dose-dependent effect (P < 0.05). Curcumin supplementation showed no influence on feed intake, fish mortality, or survival rate (P >0.05). The curcumin-treated fish groups improved tissue structure in hepatocytes, pancreatic lumens, hepatic blood sinusoids, and intestine tissue layers, particularly the mucosal layer. The T0.8 group had reduced liver enzymes (AST and ALT) and greater total protein and albumin levels (P<0.05). The T0.6 and T0.8 groups showed significantly lower MDA levels than the other groups (P < 0.05). Curcumin groups demonstrated significantly higher antioxidant indices (CAT, GPx, and SOD) compared to the basal diet (P<0.05). Curcumin administration resulted in significant improvements in IgM and lysosome levels (P<0.05). All supplemented groups had considerably (P<0.05) higher levels of SOD, CAT, and GPx mRNA than the control group. Consequently, administering 0.6–0.8 g/kg of curcumin to red tilapia (Oreochromis sp.) diets may improve the fish’s growth, health, tissue composition, and antioxidant response.

Phenotypic Convergence Is Stronger and More Frequent in Herbivorous Fishes.

Constraints on phenotypic evolution can lead to patterns of convergent evolution, by limiting the "pool" of potential phenotypes in the face of endogenous (functional, developmental) or exogenous (competition, predation) selective pressures. Evaluation of convergence depends on integrating ecological and morphological data within a robust, comparative phylogenetic context. The staggering diversity of teleost fishes offers a multitude of lineages adapted for similar ecological roles and, therefore, offers numerous replicated evolutionary experiments for exploring phenotypic convergence. However, our understanding of fish feeding systems has been primarily shaped by marine species, with the monolithic exception of freshwater cichlids. Here we use piranhas and pacus (Serrasalmidae) to explore the evolution of different feeding ecologies and their morphological proxies in Neotropical freshwater environments. Specifically, we explore whether convergence is more widespread among plant-eating fishes, arising from strong constraints on phenotypic evolution in herbivores. Using osteological micro-computed tomographic imaging (μCT), we describe the major axes of morphological variation in pacus and piranhas, regarding their diet and feeding behaviors. Next, we evaluated whether herbivorous niches are less labile than other dietary guilds and whether herbivorous species' phenotypes evolve at a slower evolutionary rate than other taxa. We then assess how convergent herbivorous taxa are, using three different suites of morphological characters (dental, jaw, and abdominal morphometrics). Ecologically, herbivory is not a dead end, exhibiting similar observed transition rates as those between carnivores and omnivores. However, we documented widespread convergence in herbivores and that herbivores have slower rates of phenotypic evolution than carnivores. Most instances of convergence are found in herbivorous taxa, specifically in frugivores and folivores. Moreover, instances of "complete" convergence, indicated by positive convergence metrics observed in more than one morphometric dataset, were only found in herbivores. Herbivores do appear to evolve under constrained circumstances, but this has not limited their ecological ability.

Chlorella vulgaris algae ameliorates chlorpyrifos toxicity in Nile tilapia with special reference to antioxidant enzymes and Streptococcus agalactiae infection

BackgroundChlorpyrifos (CPF) is a widely used pesticide in the production of plant crops. Despite rapid CPF biodegradation, fish were exposed to wastewater containing detectable residues. Recently, medicinal plants and algae were intensively used in aquaculture to replace antibiotics and ameliorate stress impacts.Methods and resultsAn indoor experiment was conducted to evaluate the deleterious impacts of CPF pollution on Nile tilapia health and the potential mitigation role of Chlorella vulgaris algae. Firstly, the median lethal concentration LC50 − 72 h of CPF was determined to be 85.8 µg /L in Nile tilapia (35.6 ± 0.5 g body weight) at a water temperature of 27.5 °C. Secondly, fish were exposed to 10% of LC50 − 72 h for six weeks, and tissue samples were collected and examined every two weeks. Also, Nile tilapia were experimentally infected with Streptococcus agalactiae. Exposed fish were immunosuppressed expressed with a decrease in gene expressions of interleukin (IL) 1β, IL-10, and tumor necrosis factor (TNF)-α. Also, a decline was recorded in glutathione peroxidase (GPx), superoxide dismutase (SOD), and catalase (CAT) gene expression in the head kidney tissue. A high mortality rate (MR) of 100% was recorded in fish exposed to CPF for six weeks and challenged with S. agalactiae. Fish that received dietary C. vulgaris could restore gene expression cytokines and antioxidants compared to the control. After six weeks of CPF exposure, fish suffered from anemia as red blood cell count (RBCs), hemoglobin (Hb), and packed cell volume (PCV) significantly declined along with downregulation of serum total protein (TP), globulin (GLO), and albumin (ALB). Liver enzymes were significantly upregulated in fish exposed to CPF pollution, alanine aminotransferase (ALT) (42.5, 53.3, and 61.7 IU/L) and aspartate aminotransferase (AST) (30.1, 31.2, and 22.8) after 2, 4, and 6 weeks, respectively. On S. agalactiae challenge, high MR was recorded in Nile tilapia exposed to CPF (G3) 60%, 60%, and 100% in week 2, week 4, and week 6, and C. vulgaris provided a relative protection level (RPL) of 0, 14.29, and 20%, respectively.ConclusionsIt was concluded that CPF pollution induces immunosuppressed status, oxidative stress, and anemic signs in Nile tilapia. In contrast, C. vulgaris at a 50 g/kg fish feed dose could partially ameliorate such withdrawals, restoring normal physiological parameters.

Pathological caudal skeleton of an ichthyodectiform fish from the Upper Cretaceous Niobrara Formation of western Kansas, USA.

A series of 12 contiguous caudal vertebrae of an ichthyodectiform fish from the Smoky Hill Chalk Member of the Niobrara Formation is described. The vertebral centra exhibit extensive overgrowth of pathological bone and there is additional pathological bone within the centra and intervertebral spaces, which together resulted in the coossification of most centra. The extent of the pathology is greatest on preural vertebrae 1-3 and decreases anteriorly, which suggests that the pathology began posteriorly and progressed anteriorly. In addition to the pathological overgrowth on bones, the specimen preserves features interpreted as calcified and/or ossified soft tissues associated with the neural and haemal canals. The pathologies are unlike previously described examples of bony pathologies in fish, and it is suggested that they resulted from combined bacterial and fungal infections. As the pathologies developed, they would have adversely impacted the fish's swimming and feeding abilities, and presumably eventually led to the fish's death.

Implications of Heavy Metal Accumulation in Fish Feed, Water, Sediment, and Different Fish Species in a Polyculture System.

Heavy metal bioaccumulation in organisms is primarily a result of dietary uptake. The current study examines the concentrations of heavy metals (Pb, Cd, Cr, and Cu) in fish feed, water, sediment, and three fish species (Catla catla, Labeo rohita, and Cyprinus carpio) from different feeding zones in a polyculture pond system. Furthermore, associated human health risks were also evaluated. The fish samples (n = 25 for each species) were collected from 10 different fish ponds in the Kohat district, Pakistan. Heavy metals were determined using an atomic absorption spectrometer. Results revealed higher concentrations of heavy metals in sediment, followed by water. However, the concentration of heavy metals in fish feed was lower than the standard limits. In the case of fish, the bottom feeder (C. carpio) notably exhibited higher (P < 0.05) levels of heavy metals than the column feeder (L. rohita) and surface feeder (C. catla) fish. Moreover, in the liver of all fish species, the bioaccumulation of heavy metals was higher, followed by the gills. Principal component analysis (PCA) demonstrated a strong correlation of heavy metals in C. carpio gills, flesh, feed, and pond water, while the heavy metals in the liver correlated with the detected metals in sediment. The human health risk analysis shows that bottom feeder fish had higher estimated daily intake (EDI), target hazard quotient (THQ), and hazard index (HI) values (> 1). Consequently, the exposed population may experience adverse health effects. The findings of this study suggest that the bottom feeder (C. carpio) bioaccumulates a higher concentration of heavy metals than column (L. rohita) and surface feeder (C. catla) in the polyculture system.

Potential of yeast (&lt;i&gt;Saccharomyces cerevisiae&lt;/i&gt;) as feed stabilizer and growth promoter on &lt;i&gt;Clarias gariepinus&lt;/i&gt; (Burchell, 1822) fingerlings

This research was carried out to examine the potential of yeast as a fish feed stabilizer and growth promoter on Clarias gariepienus with varying levels of baker’s yeast (Saccharomyces cerevisae). Clarias gariepinus fingerlings with mean weight of 2.40 grams fingerlings were obtained from Aliu Farms, Kaduna and transported to the Fishery unit located in the Zoological Garden of the school, Kaduna State University, Kaduna State Nigeria. The fish were acclimatized for two weeks in 60 Liters’ plastic tanks. Fish were stocked at 10 fingerlings per tank containing de-chlorinated tap water in triplicate. Four experimental diets with different inclusion levels of Saccharomyces cerevisiae as follows; Diet I (5%), Diet II (7.5%) Diet III (10%) and Diet IV (12.5%) and the control diet without Saccharomyces cerevisiae were formulated at 40% crude protein. Feed subjected to stability test clearly showed that stability increases with increased level of yeast with Diet IV (12.5%) having the highest at 30 minutes (76%) and 60 minutes (68%). The pelleted feeds were fed to fish at the rate of 5% of the fish biomass throughout the experimental period. The growth response was assessed in terms of daily weight gain, relative weight gain, specific growth rate, feed conversion ratio. The results showed that diet III (10%) gave the best growth performance with an average weight gain of 2.7 followed by diet IV (12.5%) of average weight gain of 2.39 g when compared to the control diet. Similarly, diet III (10%) recorded the highest survival rate of 80%. Thus, adding baker’s yeast cells into commercial fish feed at 10% improved growth and survival of Clarias gariepinus.

Effects of Frying, Freezing, Boiling, and Thawing Processes on Proximate, PH and Energy Values of Fresh (Oncorhynchus mykiss)

Objective/Background: Oncorhynchus mykiss is the most popular type of freshwater fish consumed by Iranians. It has delicious taste and high nutritional value. The purpose of processing and preserving fish is to get it to the end consumer in a good, usable condition. Methods: This study is a descriptive study that compares and determines the analysis results of proximate, protein, and fat between fresh and processed fish using the standard method of AOAC and compares the analysis of this study with that of other studies. The effect of the processing methods’ nutritional composition is determined. In addition to fresh fish, 5 treatments are used for the 5 different methods of fish processing. Results: The fresh fish and the different processed samples were analyzed by standard AOAC methods, and their pH was measured. After analyzing the macronutrient compounds of different samples, the energy values were then calculated in kcal. The moisture content ranged from 72.50% for fresh fish to 19.50% for frozen fish, while the fat content ranged from 8.09% for fresh fish to 64.47% for frozen fish. The ash contents were found to range from 4.82% to 5.82%, while the protein contents were found to range from 10.47% to 13.59%. The results showed that quick freezing of fish preserved nutrients with a high percentage of energy. This sample was recommended for consumption, followed by samples thawed in oven and in hot water. The fried and boiled samples were in the next stages of quality and energy values. Conclusions: Because the fat content of this type of fresh fish is high, and if fish feed and its nutrition are protein materials with high biological value, it will be useful to increase the percentage of meat protein for it to grow.

Safety and efficacy of a feed additive consisting of 6-phytase produced with Trichoderma reesei (CBS 126897) (Quantum® Blue) for fin fish (ROAL Oy).

Following a request from the European Commission, EFSA was asked to deliver a scientific opinion on the safety and efficacy of 6-phytase (Quantum® Blue) as a zootechnical feed additive for fin fish. The additive is authorised for use in poultry and pigs. The additive is available in solid and liquid forms, and the 6-phytase contained in the product is produced by fermentation with a genetically modified strain of Trichoderma reesei. The Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) concluded that the genetic modification of the production strain does not give rise to safety concerns; viable cells of the production strain and its DNA were not detected in the final products. The FEEDAP Panel concluded that, based on the data available, the additive tested is safe for fin fish at the highest recommended level of 2500 phytase activity unit (FTU)/kg complete feed. The Panel concluded that Quantum® Blue is not an irritant to skin and eyes nor a skin sensitiser. Owing to the proteinaceous nature of the active substance, 6-phytase (Quantum® Blue) is considered a respiratory sensitiser. The use of Quantum® Blue as a feed additive is considered safe for the environment. The additive is considered to be efficacious as a zootechnical additive for salmonids and ornamental fish at 500 FTU/kg complete feed and other fin fish at 2500 FTU/kg complete feed.

A non-microcystin-producing Microcystis wesenbergii strain alters fish food intake by disturbing neuro-endocrine appetite regulation

Cyanobacterial harmful algal blooms (cHABs) are pervasive sources of stress resulting in neurotoxicity in fish. A member of the widely distributed Microcystis genus of bloom-forming cyanobacteria, Microcystis wesenbergii can be found in many freshwater lakes, including Dianchi Lake (China), where it has become one of the dominant contributors to the lake's recurrent blooms. However, unlike its more well-known counterpart M. aeruginosa, the effects of dense non-microcystin-containing M. wesenbergii blooms are seldom studied. The disturbance of appetite regulation and feeding behaviour can have downstream effects on the growth of teleost fish, posing a significant challenge to aquaculture and conservation efforts. Here we examined the effects of M. wesenbergii blooms on the food intake of Acrossocheilus yunnanensis, a native cyprinid in southern China. This fish species has disappeared in Dianchi Lake, and its reintroduction might be negatively affected by the presence of this newly-dominant Microcystis species. We co-cultured juvenile A. yunnanensis with a non-microcystin-producing strain of M. wesenbergii at initial densities between 5 × 104 and 1 × 106 cells/mL and monitored fish feeding behaviour and changes in neurotransmitter and hormone protein levels. High-density M. wesenbergii cultures increased the feeding rate of co-cultured fish, elevating concentrations of appetite-stimulating signalling molecules (Agouti-related protein and γ-aminobutyric acid), while decreasing inhibitory ones (POMC). These changes coincided with histopathological alterations and reduced somatic indices in brain and intestinal tissues. Given this potential for detrimental effects and dysregulation of food intake, further studies are necessary to determine the impacts of chronic exposure of M. wesenbergii in wild fish.

Peningkatan Ekonomi Paska-Pandemi Melalui Pengembangan Ulat Hongkong pada Kelompok Masyarakat Pembudidaya Ikan Air Tawar “Sumber Duren” Kabupaten Malang

Senggreng Village is one of the areas in Sumber Pucung District, Malang Regency, promising to be developed in agriculture, animal husbandry, fisheries, and agro-tourism. Abundant water resources mainly support the fisheries and agriculture potency due to its position near the Sutami Dam. One of the community groups in Senggreng Village, "Sumber Duren", is "engaged in developing a small amusement park that integrates culinary, fishing park and freshwater fish farming business, managed through a cage system. Regardless of its considerable potency, fish farming has not been carried out intensively, especially due to the high prices of commercial fish feed. Therefore, this community service team proposed a solution by initiating mealworm (Tenebrio molitor) cultivation as a cheap, high-protein, and sustainable source of fish feed to increase crop yields. Experienced mealworm practitioners also provided intensive mealworm cultivation education, training, and profitable business planning. Through this program, the community group "Sumber Duren" has been" successful in cultivating mealworms starting from the seedling phase to becoming broodstock and laying eggs. Based on the questionnaire data collection, most community group members stated that this community service activity helped provide new knowledge interested in cultivating alternative feeds, and 80% of respondents expected the activity to continue in the following years.