This review presents several alternatives to replace antibiotic therapy and make the European aquaculture industry more friendly and environmentally sustainable. The first part of this review highlights the growing importance of the aquaculture industry worldwide for its ability to supply low-cost proteins and lipids. The second part discusses different strategies for these replacements, from recombinant vaccines to diets with low environmental impact and rich in bioactive molecules that can benefit other species. Specifically, the beneficial effects of bioactive compounds present within insect meals are discussed. In addition, particular focus is placed on the importance of adopting sustainable protocols for fish farming, including supplements such as probiotics, prebiotics, and synbiotics capable of modulating the gut microbiota as the second brain. Those feed additives can stimulate European farmed species’ immunological systems, growth, and welfare.

Polydatin is a polyphenol, whose beneficial properties, including anti-inflammatory and antioxidant activity, have been largely demonstrated. At the same time, copper has an important role in the correct organism homeostasis and alteration of its concentration can induce oxidative stress. In this study, the efficacy of polydatin to counteract the stress induced by CuSO₄ exposure or by caudal fin amputation was investigated in zebrafish larvae. The study revealed that polydatin can reduced the stress induced by a 2 h exposure to 10 µM CuSO₄ by lowering the levels of il1b and cxcl8b.1 and reducing neutrophils migration in the head and along the lateral line. Similarly, polydatin administration reduced the number of neutrophils in the area of fin cut. In addition, polydatin upregulates the expression of sod1 mRNA and CAT activity, both involved in the antioxidant response. Most of the results obtained in this study support the working hypothesis that polydatin administration can modulate stress response and its action is more effective in mitigating the effects rather than in preventing chemical damages.

When environmental conditions change, microalgae can modulate the size of their macromolecular pools and their elemental composition in order to accommodate their nutritional and energetic demands. In this context, we evaluated how O₂ levels and S starvation alter the resource partitioning in terms of organic and elemental composition in Chlamydomonas reinhardtii. The analysis of gene transcription, photosynthetic energy production and organic pool allocation allowed us to identify a two-phase cellular response related to external O₂ concentration: (1) a short-term response where S starvation induced the expression of S starvation genes immediately after the start of the perturbation; (2) a long-term response that consisted of a drastic reduction of photosynthetic energy production and changes in C allocation following S deprivation, which was related to oxygen conditions. In anaerobic conditions, S starvation did not affect the pools of carbohydrates and lipids, whereas the protein pool decreased slightly over time. On the other hand, in aerobic conditions, S starvation modulated all organic pools: carbohydrates, lipids and proteins. We conclude that the energy levels produced by fermentation metabolism are not sufficient to sustain the acclimation process in C. reinhardtii; moreover, S availability affects C. reinhardtii more than do oxygen levels.

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.