Rafael Queiroz dos Anjos

Self-feeding systems have been used to study aquatic animals’ behavior, suggesting initial studies for practical diet design. This study aimed to identify gaps in knowledge of the behavior, feeding rhythms, and target protein intake of the Amazon River prawn ( Macrobrachium amazonicum ) to inform the design of new diets. This study included two trials. In trial 1, under a 12:12 h LD photoperiod, 40 prawns (mean ± SD = 2.18 ± 0.3 g) were divided into four experimental units. A self-feeding system connected by an infrared sensor was prepared. Prawns were allowed to trigger sensors connected to feeders to assess a possible daily feeding rhythm for 52 days. During trial 2, 80 prawns (1.55 ± 0.19 g) were placed inside eight aquariums. The effect of two dietary protein levels (20%P or 40%P) was evaluated on behavioral protein intake target using self-feeding, as well as growth and body composition. The results of trial 1 showed that Amazon River prawn exhibited predominantly nocturnal behavior using self-feeding systems, with higher food intake during this period ( p < 0.05). However, crepuscular behavior was also observed. The trial 2 results revealed a clear protein intake target of 2.4 g per 100 g of body weight (BW). After the diet was switched from 40 to 20P, the prawns’ feed intake increased ( p < 0.05) to compensate for the protein dilution. Diet 40P had significant effects on final weight, weight gain, length gain, specific growth rate and feed efficiency ( p < 0.05). However, diets had no influence on body composition ( p > 0.05). These findings can help to understand feed schedules and nutritional approaches, which are important for new aquaculture species.

The global expansion of intensive shrimp farming confronts a physiological paradox: while production systems become increasingly technological, management protocols often disregard the temporal dimension of crustacean physiology. This study presents a comprehensive bibliometric analysis of shrimp chronobiology based on 197 Scopus-indexed publications (1943-2026). Network analysis reveals a conceptual transition from descriptive ecological studies (1950s-1990s) focused on tidal rhythms and catchability to a contemporary molecular frontier (2015-2025) driven by transcriptomics, clock gene expression, and immune-circadian interactions. Keyword co-occurrence analysis identified four structural clusters: Production/Feeding, Behavior/Locomotion, Molecular Physiology, and Toxicology. Analysis of the most-cited and recent articles demonstrates that while light and feeding have been validated as primary zeitgebers, a critical knowledge gap persists regarding circadian regulation of osmotic stress. Despite the dominance of inland low-salinity farming, none of the top-ranked studies investigated rhythmic osmoregulation. We identify the lack of research on circadian regulation of osmotic stress as a significant knowledge gap and propose a research agenda integrating chronobiology into precision aquaculture to optimize metabolic efficiency and disease resistance.

The use of by-products from the fishing industry in human food constitutes a strategy aligned with the principles of the circular economy and food security. This study aimed to develop and characterize a whole wheat bread enriched with fish protein concentrate (FPC), using propolis and chitosan as natural preservatives to replace calcium propionate. Three formulations were prepared: a control (without FPC) and two formulations with partial replacement of whole wheat flour by 1.5% (T15) and 3% (T30) of FPC. Initially, all formulations were subjected to microbiological analyses and sensory evaluation. Based on the sensory results, the formulation with the highest acceptance, along with the control formulation, was selected for analyses of proximate composition, yield, water activity, colorimetric parameters, and lipid peroxidation (TBARS). The microbiological results indicated compliance with current legislation, demonstrating the product¢s safety. In the sensory analysis, no statistically significant differences were observed among the formulations for the evaluated attributes. However, formulation T30 showed an acceptability index (AI) ≥ 70%, the highest among the enriched formulations. This formulation showed approximately 25% increase in protein content compared to the control, without significant differences in moisture, lipid, and carbohydrate contents, or in technological parameters, water activity, instrumental color, and oxidative stability. It is concluded that whole wheat bread enriched with 3% FPC and preserved with propolis and chitosan is technologically viable, microbiologically safe, and sensorially acceptable, configuring itself as a nutritious and sustainable alternative for the valorization of by-products from the fishing industry.

Oxidative instability represents a critical barrier to the practical application of essential oils as functional additives in aquaculture feeds. This study evaluated the oxidative resistance of three commercially relevant essential oils: cinnamon leaf (Cinnamomum verum), peppermint (Mentha piperita), and tea tree (Melaleuca alternifolia), under conditions simulating feed processing and storage, including UV-C radiation (254 nm) and elevated temperature (60 ºC) for up to 48 hours. Chemical composition was determined by GC-MS, and lipid peroxidation was quantified by malondialdehyde (MDA) accumulation using the TBARS method. The results revealed a clear relationship between chemical profile and oxidative stability. Tea tree oil exhibited greater oxidative resistance, with lower MDA levels compared to cinnamon leaf and peppermint oils after 48 hours of thermal and UV stress (p < 0.05). These findings indicate that oxidative stability is a criterion for technical and economic feasibility in the selection of essential oils for aquaculture. While tea tree oil shows high potential for direct application, the use of unstable oils depends on the development of technological protection strategies, thereby redirecting research and development efforts toward economically viable formulations.