The formulator of aquatic diets is part of a continuous search for alternative protein sources instead of depreciated fish meal. The utilization of zooplankton as a feed ingredient is an interesting trend due to their high-quality protein content and abundance of essential nutrients. The current study aims to investigate the effects of partial and total replacement of fish meal (FM) by Dahpnia magna meal (DMM) on growth performance, feed utilization, histological, and economic status of mullet, M. cephalus, larvae. In addition to the control diet, 100% FM, D₀, four diets containing DMM at different levels were used: 25% (D₂₅), 50% (D₅₀), 75% (D₇₅), and 100% (D₁₀₀) replacement of fish meal. A total of 300 larvae (0.097 ± 0.001 g) were equally divided into five groups (three replicate per each group) at a density of 200 larvae m⁻³. The aquariums were renewed at a rate of 30% daily. During the 60-day experimental period, all larvae were fed their respective diets at a level of 20% of live body weight, five times a day (9.00 a.m., 12.00, 15.00, 18.00, and 21.00 p.m.). The results indicated that compared to D₀, fish fed D₇₅ recorded the highest significant value of growth, and feed utilization parameters, while fish fed D₁₀₀ achieved the lowest feed cost and incidence cost, and the highest profit index and economic efficiency ratio. A strong correlation was reported among weight gain, feed conversion ratio and fish meal replacement with DMM; R² = 0.94 and 0.91, respectively. The fit regression model representing mullet response to FM replacement with DMM is a poly-nominal regression model with maximum response at 75–100%. The histological investigation of the intestine revealed an improvement of histomorphometric indices and goblet cell number with increasing DMM inclusion levels. These findings confirmed that 75% to 100% partial substitution of FM with DMM is the ideal replacement for mullet, M. cephalus, larvae for improving fish growth performance and feed utilization.

Fishmeal is the most expensive feedstuff in the aquafeed and one of the most environmentally limiting factor of aquaculture development. Therefore, the search for alternative protein sources is a continuous process. The present feeding trial was conducted to evaluate the effects of replacing fishmeal with zooplankton biomass meal (ZBM) on the growth performance, nutrient utilization, intestine, and liver histological changes of grey mullet, Mugil cephalus (initial weight of 0.10 ± 0.01 g). Five isoproteic (35% crude protein) and isolipidic (8% crude lipid) diets were formulated as the control diet (Z₀) and the other four diets (Z₂₅, Z₅₀, Z₇₅, and Z₁₀₀), where 25%, 50%, 75%, and 100% of fishmeal was replaced by ZBM, respectively. After 60 days of feeding, the final weight, weight gain, and daily growth index of the grey mullet fed the Z₁₀₀ diet were higher than those fed the control diet (p < 0.05). In addition, the better values of feed conversion ratio, protein efficiency ratio and lipid efficiency ratio were recorded in the fish fed with the Z₁₀₀ diet. Additionally, the intestinal villus length, crypts depth, and muscle thickness were significantly improved with ZBM inclusion (p < 0.05). Meanwhile, there were no histopathological changes observed on the liver when compared with the control group. From the economic point of view, dietary substitution of fishmeal by ZBM (Z₁₀₀) reduced the cost of diet formulation by 18% and the price per kg weight gain by about 40%. Overall, according to the findings of this study, substituting fishmeal with ZBM up to 100% could improve growth performance, feed utilization, gut health status, and profit ability of rearing M. cephalus juveniles.

The future of aquaculture development is directed toward high intensification to overcome the decline in natural fishing and to provide enough protein for the increasing world population. The spread of aquaculture production and intensification requires the search for high-quality, new efficient feed ingredients with low cost and sustainable importance. Therefore, the current study aimed to detect the effects of partial or total replacement of fishmeal with amphipod meal, Gammarus pulex, on growth performance, survival percent, feed utilization, histological alteration of intestine and liver, and economic yield of grey mullet, Mugil cephalus, fry. Five diets were formulated to contain 100% fishmeal (FM), or FM replaced with 25%, 50%, 75%, or 100% amphipod meal (APM) (D₀, D₂₅, D₅₀, D₇₅, and D₁₀₀, respectively). A total of 300 grey mullet fry (0.097 ± 0.001 g), were divided into five groups (three replicates each) at an initial stocking density of 20 fry per aquaria (100 L). The aquarium’s water is renewed at a rate of 30% daily. During a 60-day experimental period, the feeding rate was 20% of body weight, which was introduced as five meals per day. Fish fed D₅₀ achieved the highest significant values of final weight (1.80 g), weight gain (1.70 g), survival (86.67%), final length (4.47 cm), and length gain (2.06 cm). In addition, the feed utilization of diets containing increasing substitution levels of FM showed that the highest protein intake (0.82 g ish⁻¹), protein efficiency ratio (0.83), protein productive value (30.65%), and the lowest significant feed conversion ratio (1.21) were recorded with D₅₀. The dose-response study revealed that the best substitution levels could range between 50% and 75%. Histological observations confirmed that the highest number of goblet cells and intestinal villi were recorded in the group fed D₅₀. No pathological effect was observed in the liver at all substitution levels. In terms of economic efficiency, the best economic conversion ratio was recorded in the group fed D₅₀. This study confirmed that 50% partial substitution of FM with APM is the ideal replacement level for grey mullet fry. In addition, the use of a new renewable alternative, such as APM to substitute FM, could relieve the pressure on the capture of wild fish and reduce the environmental impact of inland aquaculture.

In this study, a sustainable and eco-friendly method was used to prepare zinc oxide nanoparticles (ZnO-NPs) using a sea cucumber aqueous extract. Then, ZnO-NPs were characterized by instrumental analysis (UV-vis, HR-TEM, XRD, FT-IR, and DLS) and evaluated for their possible antibacterial, antifungal, and insecticidal activities. Additionally, the toxicity of ZnO-NPs was evaluated in vivo against Nile Tilapia (Oreochromis niloticus). The sea cucumber was collected from the Gulf of Suez (Red Sea) at Al-Ain Al-Sokhna coast in Egypt and identified as Holothuria impatiens. The prepared Hi-ZnO-NPs peaked at 350 nm in UV–Vis spectral analysis. They showed quasi-spherical shaped particles with sizes ranging from 13 nm to 47 nm and a predominate size of 26 nm as indicated by HR-TEM. The XRD pattern of Hi-ZnO-NPs revealed a crystalline phase with an average size of 17.2 nm as calculated by Debye–Scherrer equation. FTIR analysis revealed the possible role of H. impatiens biological molecules in the biosynthesis process of ZnO-NPs. Hi-ZnO-NPs showed a negative zeta potential of −19.6 mV, demonstrating moderate stability. Biosynthesized Hi-ZnO-NPs revealed broad antimicrobial activity against Gram-positive bacteria (S. aureus ATCC 25923 and E. feacalis), Gram-negative bacteria (S. typhi, K. pneumonia and E. coli), and filamentous fungi (Aspergillus niger). Hi-ZnO-NPs demonstrated larvicidal activity against the mosquito, Culex pipiens (LC₅₀ = 2.756 ppm and LC₉₀ = 9.294 ppm), and adulticidal action against the housefly, Musca domestica (LD₅₀ = 4.285 ppm and LD₉₀ = 22.847 ppm). Interestingly, Hi-ZnO-NPs did not show mortality effects against Nile tilapia fish (Oreochromis niloticus), highlighting the potential safety of Hi-ZnO-NPs to highly exposed, non-target organisms. However, histopathological and hematological investigations provided dose-dependent impacts of Hi-ZnO-NPs to Nile tilapia. Overall, data provide an eco-friendly approach for synthesizing novel Hi-ZnO-NPs with multiple biomedical properties and potentially low toxicity to Nile tilapia fish.

The marine environment is a rich source of bioactive compounds. Therefore, the sea cucumber was isolated from the Red Sea at the Al-Ain Al-Sokhna coast and it was identified as surf redfish (Actinopyga mauritiana). The aqueous extract of the surf redfish was utilized as an ecofriendly, novel and sustainable approach to fabricate zinc oxide nanoparticles (ZnO-NPs). The biosynthesized ZnO-NPs were physico-chemically characterized and evaluated for their possible antibacterial and insecticidal activities. Additionally, their safety in the non-target organism model (Nile tilapia fish) was also investigated. ZnO-NPs were spherical with an average size of 24.69 ± 11.61 nm and had a peak at 350 nm as shown by TEM and UV-Vis, respectively. XRD analysis indicated a crystalline phase of ZnO-NPs with an average size of 21.7 nm. The FTIR pattern showed biological residues from the surf redfish extract, highlighting their potential role in the biosynthesis process. DLS indicated a negative zeta potential (−19.2 mV) of the ZnO-NPs which is a good preliminary indicator for their stability. ZnO-NPs showed larvicidal activity against mosquito Culex pipiens (LC₅₀ = 15.412 ppm and LC₉₀ = 52.745 ppm) and a potent adulticidal effect to the housefly Musca domestica (LD₅₀ = 21.132 ppm and LD₉₀ = 84.930 ppm). Tested concentrations of ZnO-NPs showed strong activity against the 3rd larval instar. Topical assays revealed dose-dependent adulticidal activity against M. domestica after 24 h of treatment with ZnO-NPs. ZnO-NPs presented a wide antibacterial activity against two fish-pathogen bacteria, Pseudomonas aeruginosa and Aeromonas hydrophila. Histopathological and hematological investigations of the non-target organism, Nile tilapia fish exposed to 75–600 ppm ZnO-NPs provide dose-dependent impacts. Overall, data highlighted the potential applications of surf redfish-mediated ZnO-NPs as an effective and safe way to control mosquitoes, houseflies and fish pathogenic bacteria.

Nanomaterials are increasingly used in manufacturing, medicine, consumer products, and environmental technologies due to their unique physicochemical properties. Although these materials offer substantial technological and societal benefits, their widespread use has raised concerns about potential health risks. Of particular importance is exposure during pregnancy, as certain nanoparticles can cross the placental barrier and reach the developing embryo. Fetal tissues are highly sensitive to environmental insults, so maternal exposure to nanoparticles may disrupt normal development and increase the risk of abnormal pregnancy outcomes. This review examines the current understanding of nanoparticle-induced developmental toxicity, with a focus on the vulnerability of the maternal–fetal unit. We discuss the structure and function of the placental barrier and the mechanisms that enable nanoparticle transfer from mother to fetus. Particular attention is given to how nanoparticle characteristics, including size, shape, composition, and surface chemistry, influence biodistribution, placental transport, tissue accumulation, and toxicity. We summarize the major molecular and cellular mechanisms implicated in fetotoxicity, highlighting oxidative stress, apoptosis, autophagy, and DNA damage as recurring pathways identified across experimental studies. These interconnected processes contribute to placental dysfunction, impaired fetal growth, developmental abnormalities, and adverse pregnancy outcomes. We also compare findings across different classes of nanoparticles, including metal, metal oxide, carbon-based, and polymeric nanomaterials, identifying both shared toxicological mechanisms and material-specific effects. Evidence from animal models demonstrates that susceptibility varies according to nanoparticle properties, exposure conditions, and species, underscoring the complexity of nanoparticle–biological interactions and the limitations of extrapolating experimental findings directly to humans. Overall, the available evidence indicates that nanoparticle exposure during pregnancy represents a potential risk to fetal health, although important knowledge gaps remain regarding human exposure and long-term developmental outcomes. A better understanding of the mechanisms underlying nanoparticle-induced fetotoxicity is essential for improving human health risk assessment, refining experimental models, informing regulatory policies, and supporting the safe-by-design development of nanomaterials. Such knowledge will help ensure the responsible application of nanotechnology while minimizing potential risks during pregnancy. Finally, this review is distinguished by its integrated analysis of how the chemical characteristics of nanoparticles govern placental transfer and the mechanistic pathways of fetotoxicity across multiple nanomaterial classes, providing a unified framework that connects material properties with their potential for abnormal fetal development and adverse pregnancy outcomes.