Sustainable Ornamental Fish Aquaculture: The Implication of Microbial Feed Additives

The Assessment of Natural Biomineral Leonardite on Growth and Pigmentation of Goldfish, Carassius auratus

In this study, the impact of leonardite as a feed additive in goldfish diets was examined, focusing on its potential to positively influence feed and water parameters, which are critical for achieving sustainable ornamental fish farming. In this study, goldfish were fed diets containing four different levels of leonardite (0%, 2%, 6%, 10%). The experiment was conducted in 12 tanks with 3 replicates per treatment and lasted for 3 months. The fish, which were provided from the Research, Production and Training Institute, with an average live weight of 0.947 ± 0.03 g and an average length of 1.12 ± 0.02 cm, were used. After 90 days, it was observed that the specific growth rates increased in correlation with the amount of leonardite in the diet, with a statistically significant difference identified (p < 0.05). In this study, which investigated the coloration of fish with leonardite added to the feed for the first time, it was determined that the color of the fish approached from yellow to orange as the amount of leonardite added to the feed increased (p < 0.05). Given the positive effects observed on pigmentation and growth in this study, it is recommended that further detailed investigations be conducted on leonardite, a natural, harmless, and cost-effective additive, using different fish species.

Integrative use of DNA barcode and morphology reveal high level of diversity in the ornamental fish on the lower Amazon basin

The Amazon basin is the world's largest hydrographic basin, in terms of both its total area and its species diversity, with more than 2,700 species of fish. Despite this diversity, the data available on the fish fauna of the Amazon basin are still relatively scant and incomplete, in particular from the streams and floodplain lakes of the lower Amazon, which may contain a large proportion of the still undescribed species of the basin. Many of these species are expected to be of interest to the ornamental fish market. The investigation of the diversity of potential ornamental fish using molecular tools is even more limited. Given this scenario, the present study employed DNA barcoding to investigate the diversity of ornamental fish found in two streams and a floodplain lake of the lower Amazon. The mitochondrially encoded cytochrome c oxidase I (MT-CO1) molecular marker was used to identify the taxa, in combination with morphological keys. A total of 51 ornamental species were identified, representing 13 families and three orders. A majority of the species were found at only one of the sampling points, which indicates that the distribution of the species is influenced by ecological factors. The most speciose order was the Characiformes, followed by the Cichliformes and Siluriformes, while the family with the greatest diversity of species was the Acestrorhamphidae (31.3% of the total number of species), followed by the Cichlidae (27.4%), and the Lebiasinidae (9.8%). One specie was registered in the region of the lower Amazon for the first time, and evidence was found of the possible existence of species not formally described of Aphyocharax, Astyanax, Apareiodon and Hemigrammus.

Tranquilizing and hepatoprotective effects of red-eye tetra (Moenkhausia Forestii) diet fed with Erythrina crista-galli

This study aimed to assess the leaf aqueous extract composition of Erythrina crista-galli and the effects of its inclusion on the diet of red-eye tetra (Moenkhausia forestii), concerning enzyme content of digestive, hepatic, and oxidation metabolism and pigmentation. Fish (1.78 ± 0.54 g) were divided into groups: fasting (without feeding), control (commercial feed), and treatment (commercial feed with leaf aqueous extract of E. crista-galli) and feeding apparent satiety for 21 days, in the extracted analysis by mass spectrometry, phenolic compost, and flavonoids. The agitation degree and number of dashes, in all supplemented treatments, were lower than those in the control diet when fed for 7 or 15 days. In the digestive enzymatic activity did not differ (p > 0.05). The hepatoprotective treatment group showed lower alanine aminotransferase (ALT) and higher levels of antioxidant catalase (CAT). The results indicated that the aqueous leaf extract of Erythrina crista-galli assists in function maintenance of the liver; and stimulates CAT in red-eye tetra, suggesting that the identified compounds act on the liver and skin, showing hepatoprotective effects and stimulating tranquility.

Exploration of the advantages of targeted isolation of deep-sea microorganisms and genetically engineered strains

Oil, mineral processing and environmental restoration can be dangerous processes. Attempts are often made to apply microorganisms to reduce the risks, but the adaptability of terrestrial organisms is often weak. Although genetically engineered strains can improve their environmental adaptability through targeted modification, there are problems such as metabolite accumulation, poor plasmid stability and potential pathogenicity. Screening of extremophiles from the natural environment has become an inevitable choice. The special environment in the deep sea (high pressure, low temperature, low nutrition, high salinity) is a natural place for extremophiles to grow and survive, thus screening of extremophiles from the deep sea is conducive to the green and sustainable development of industry. In this paper, the application status and problems of genetically engineered strains are reviewed based on the microorganisms needed for extreme industry. This paper focuses on the application status and advantages of deep-sea microorganisms. It is found that their advantages are strong adaptability, stable gene, friendly environment, simple and convenient technology (compared with genetic engineering), which has a broad industry processes application prospect. This review broadens the scope of microbial applications.

First Feeding of Cuttlefish Hatchlings: Pioneering Attempts in Captive Breeding

In the last few decades, the cuttlefish market has grown to approximately 14% of the world's fisheries, and operators have begun to express concerns about the decline of this resource. In this context, the production of cuttlefish through aquaculture could offer a diversifying and valuable response to the increasing market demand and help alleviate the environmental pressure on this species. Therefore, the aim of this study is to identify a dry, cost-effective, and easy-to-administer diet that can successfully support the initial phases of cuttlefish growth and provide a similar performance to a krill-based diet, which closely mimics their natural diet. To achieve this objective, cuttlefish hatchlings were distributed among different experimental tanks, each receiving one of the five different diets (namely Diets A to E). Mortality and morphological parameters were monitored until day 10 post hatching, and the two most effective diets (Diets A and B) were chosen for further trials. The results indicated that Diet B had similar survival and growth rates to Diet A, which was based on frozen krill. Histological analysis revealed a comparable degree of gut maturity between the organisms fed the two diets. Likewise, levels of amylase and trypsin enzymes and hsp70, cat, and sod mRNA did not exhibit significant differences between the two groups. In conclusion, our findings provide preliminary evidence supporting the possibility of cultivating cuttlefish in captivity using a pelleted diet, representing a promising starting point for larger-scale breeding efforts.

Bridging aquatic invasive species threats across multiple sectors through One Biosecurity

Understanding the magnitude of biosecurity risks in aquatic environments is increasingly complex and urgent because increasing volumes of international shipping, rising demand for aquaculture products, and growth in the global aquarium trade, are accelerating invasive alien species spread worldwide. These threats are especially pressing amid climate and biodiversity crises. However, global and national biosecurity systems are poorly prepared to respond because of fragmented research and policy environments, that often fail to account for risks across sectors or across stakeholder needs and fail to recognize similarities in the processes underpinning biological invasions. In the present article, we illustrate the complex network of links between biosecurity threats across human, animal, plant, and environment sectors and propose a universal approach to risk assessment. One Biosecurity is a holistic, interdisciplinary approach that minimizes biosecurity risks across human, animal, plant, algal, and ecosystem health and is critical to reduce redundancy and increase cross-sectoral cohesion to improve policy, management, and research in aquatic biosecurity.

Dietary Effect of Withania somnifera Root Powder on Growth, Hematobiochemical Parameters, Immunity, and Disease Resistance to Aeromonas hydrophila in Cyprinus carpio

This study investigates the influence of Withania somnifera root powder (WSRP) on different aspects of common carp (Cyprinus carpio), including growth, hematobiochemical parameters, antioxidant status, nonspecific immune response, and resilience to bacterial infections. Over a 60-day period, 180 common carp fingerlings (11.73 ± 0.52 g) were subjected to diets supplemented with increasing WSRP levels (0 (control), 1% (WSRP1), 2.5% (WSRP2.5), and 4% (WSRP4)). Nonspecific immune parameters were evaluated using serum samples collected at intervals of 0, 20, 40, and 60 days. After the feeding trial, the fish underwent experimental challenge with Aeromonas hydrophila, and relative percentage survival (RPS) was monitored for 14 days. The findings revealed a considerable (p  < 0.05) enhancement in growth performance and a decreased feed conversion ratio (FCR) with increasing WSRP supplementation. Additionally, hematological and biochemical profiles exhibited improvements in groups receiving WSRP-enriched diets. Fish serum antioxidant status showed a significant (p  < 0.05) increase, as indicated by increased activities of total antioxidant capacity (TAC), superoxide dismutase (SOD), catalase (CAT), and reduced glutathione (GSH) in WSRP4. WSRP-supplemented diets led to remarkable enhancements in lysozyme activity (p = 0.001), phagocytic activity (p = 0.002), and RPS (p = 0.003), peaking in WSRP4 at day 60. Furthermore, WSRP2.5 and WSRP4 demonstrated a substantial decrease (p  > 0.05) in serum glucose and cortisol levels compared to other groups. In conclusion, WSRP proves valuable for enhancing growth, blood parameters, antioxidant balance, immune response, and infection resistance in common carp, especially at 2.5%-4% dietary supplementation levels. In the future, it will be crucial to study the long-term effects of WSRP supplementation on fish health, as well as its potential for large-scale aquaculture and economic viability in the aquafeed industry.

Diagnosis, isolation and description of a novel amnoonvirus recovered from diseased fancy guppies, Poecilia reticulata

The guppy, Poecilia reticulata, is one of the most common cultured ornamental fish species, and a popular pet fish highly desired by hobbyists worldwide due to its availability of many brilliantly coloured fish of many varieties. The susceptibility of guppies to diseases presents a remarkable concern for both breeders and hobbyists. In this study, we report the emergence of disease in fancy guppies caused by a previously uncharacterized virus in the USA. This virus was isolated from moribund guppies in two separate outbreaks in California and Alabama, from December 2021 to June 2023. The infected guppies presented with acute morbidity and mortality shortly after shipping, displaying nonspecific clinical signs and gross changes including lethargy, anorexia, swimming at the water surface, gill pallor, mild to moderate coelomic distension and occasional skin lesions including protruding scales, skin ulcers and hyperaemia. Histological changes in affected fish were mild and nonspecific; however, liver and testes from moribund fish were positive for Tilapia lake virus (TiLV), the single described member in the family Amnoonviridae, using immunohistochemistry and in situ hybridization, although the latter was weak. A virus was successfully recovered following tissue inoculation on epithelioma papulosum cyprini and snakehead fish cell lines. Whole genome sequencing and phylogenetic analyses revealed nucleotide and amino acid homologies from 78.3%-91.2%, and 78.2%-97.7%, respectively, when comparing the guppy virus genomes to TiLV isolates. Based on the criteria outlined herein, we propose the classification of this new virus, fancy tailed guppy virus (FTGV), as a member of the family Amnoonviridae, with the name Tilapinevirus poikilos (from the Greek 'poikilos', meaning of many colours; various sorts, akin to 'poecilia').

The growth performance and parasite load of angelfish juveniles Pterophyllum scalare kept at different stocking densities in two rearing systems

This study evaluated the growth performance and parasite load of angelfish juveniles Pterophyllum scalare kept at different stocking densities using two rearing systems. The experiment was conducted in a factorial design (4x2) with four stocking densities (0.1, 0.4, 0.7, and 1.0 g/L), two type of aquarium tanks (glass and ceramic aquariums), and four replicates. The experiment lasted 60 days using 148 juvenile fish (3.05 ± 0.09 g) randomly placed in 32 aquariums (50 L) equipped with filters and aeration. All fish received two meals a day ad libitum (8:00 and 16:00). Water quality parameters such as temperature, dissolved oxygen, pH, and total ammonia were measured. At the end of the experiment, all fish were measured and weighed to determine growth performance and then subjected to parasitological analysis. The data were analyzed with a two-way ANOVA with post-hoc Tukey test (p<0.05). No effects on growth performance at different stocking densities were observed. However, there was an increase in Capillaria pterophylli infestation in the high stocking density within ceramic aquariums. Thus, this study recommends the use of 1.0 g/L for the intensive aquaculture system of freshwater angelfish, and applying cleaning management to avoid parasite infestation, particularly in ceramic aquariums.