Different fertilization regimes in biofloc systems influence the predominance of distinct bacterial populations, impacting water quality and organism performance. This study evaluates the growth and nutrient absorption of the macroalgae Ulva lactuca when cultivated in an integrated system with Penaeus vannamei and Oreochromis niloticus in chemoautotrophic and heterotrophic systems. The experiment lasted 45 days and comprised two treatments, each with three replicates: chemoautotrophic—utilizing chemical fertilizers; heterotrophic—employing inoculum from mature biofloc shrimp cultivation, supplemented with organic fertilizers. Each treatment consisted of three systems, each containing a 4 m³ tank for shrimp, 0.7 m³ for tilapia, and 0.35 m³ for macroalgae, with continuous water circulation between tanks and constant aeration. Water quality analyses were carried out during the experiment, as were the performances of the macroalgae and animals. The data were subjected to a statistical analysis. Results revealed an increase in macroalgae biomass and the removal of nitrate (57%) and phosphate (47%) during cultivation, with a higher specific growth rate observed in the chemoautotrophic treatment. Nonetheless, the heterotrophic treatment exhibited higher levels of protein in the macroalgae (18% dry matter) and phosphate removal rates (56%), along with superior maintenance of water quality parameters. Tilapia performance varied across treatments, with a higher final weight and weight gain recorded in the heterotrophic treatment. The recycling of water from an ongoing biofloc cultivation with organic fertilization demonstrated viability for macroalgae cultivation within an integrated system involving shrimp and fish.

Integrated multitrophic aquaculture (IMTA) emerges as a sustainable strategy to control the excess of solids and inorganic nutrients that tend to increase in the biofloc system (BFT) cycle, since the model integrates organisms from different trophic levels sharing the same system and nutrients. Thus, this study compared a Penaeus vannamei monoculture system with an integrated biofloc system including Mugil liza, Holothuria grisea, Crassostrea tulipa, and Salicornia neei, focusing on water quality and the performance of organisms and systems. This study consisted of three monoculture systems (16 m³; 375 shrimp m⁻³) and three IMTA systems, composed of a shrimp tank (16 m³), a mullet tank (4 m³; 30 ind m⁻³), a combined tank (3 m³) for oysters (45 ind m⁻³) and sea cucumbers (3 ind m⁻²), and a Salicornia neei bed (2.78 m²; 37 ind m⁻²). All IMTA systems operated in recirculation without water exchange, using 10% of the established biofloc inoculum. The IMTA system had half the hydrated lime use (2.13 vs. 4.29 kg), lower solids (299.56 vs. 373.33 mg L⁻¹), and reduced sludge production (9.37 vs. 15.87 kg). Shrimp growth was similar in both systems. Mullet grew adequately with a survival rate of 95.8%, but oysters showed a survival rate of 45.7%. Sea cucumber had a survival rate of 100% until day 28, when a marked decline appeared, strongly correlated with rising temperature (>28 °C; r = −0.71). This resulted in a significant increase in solids in the last weeks, suggesting that the population decline reduces solids control capacity. Furthermore, the biofloc in IMTA was dominated by coccoid forms, with lower proportions of filamentous and cyanobacterial forms.

Wild fish populations face growing threats from anthropogenic activities, climate change, and natural disasters. Aquatic germplasm banking is a vital strategy for preserving genetic diversity and supporting sustainable aquaculture. This study proposes a sequential, decision-guided framework for developing species-specific sperm cryopreservation protocols, applied here to the endangered Pogonias courbina, listed as endangered in Brazil and vulnerable by the IUCN. A series of experiments was conducted to identify optimal conditions for thawing (26 °C for 14 s), equilibration time (10 min), extenders (HBSS, 3% glucose, 5% glucose), and both permeable (dimethyl sulfoxide, propylene glycol, dimethylformamide, ethylene glycol) and non-permeable cryoprotectants (glucose, fructose, sucrose, trehalose, skimmed powdered milk, egg yolk). Sperm quality was assessed using Computer-Assisted Sperm Analysis (CASA). Three treatments with the highest post-thaw motility (MOT) were selected to fertilize oocytes from two hormonally-induced females. No significant difference was observed between sperm from wild and farmed males. The best kinetic parameters and fertilization rates were obtained using the combination of HBSS +10% DMSO +5% egg yolk (MOT: 71.8%). Based on these findings, we propose practical recommendations regarding extender selection, equilibration time, cryoprotectant combinations, and thawing conditions that support high post-thaw viability and successful fertilization. This is the first study to report successful artificial reproduction of P. courbina using cryopreserved sperm, establishing a reproducible protocol that can be applied for captive breeding, restocking, and germplasm banking. The proposed framework offers a generalizable approach for developing cryopreservation protocols in fish species.

Aquaponics is an alternative agricultural practice that combines aquaculture with hydroponics. It increases productivity while treating macronutrient loads on effluents. Yet, little information is available on productivity of commercial aquaponic models using saline waters, especially with biofloc technology (BFT) systems, which are characterized by high concentrations of total suspended solids and nitrate. This experiment evaluated the productivity and nutritional quality of the halophytes celery ( Apium graveolens var. tall Utah) and sea asparagus ( Salicornia neei ), and the growth of a coastal fish, the Southern black drum ( Pogonias courbina ) in coupled aquaponic cultivation with clear water and BFT water. No previous report was found in the literature regarding celery cultivation coupled with saline BFT. The experiment was carried out for 18 weeks with a water salinity of 10 g L ⁻¹ . Floating rafts with halophytes (≈20 plants m ⁻² per species) were placed inside tanks holding juvenile Southern black drums (21 ind m ⁻³ ). Each water‐treatment type was tested in three replicate tanks (15 m ³ ). Both S. neei and A. graveolens produced more aboveground biomass in the BFT system than in clear‐water tanks, with average shoot yields of 0.64 and 0.23 kg m ⁻² 30 days ⁻¹ , respectively. The protein content of A. graveolens was significantly higher in BFT system, likely due to increased nitrogen availability. S. neei shoots showed highest P content in clear water, suggesting that the higher alkalinity and pH in the BFT system may have reduced P uptake. The growth of P. courbina fry did not differ significantly between treatments. Southern black drum, celery, and sea asparagus can be successfully cocultured in a biofloc‐based aquaponic system.

In this work, we describe lesions produced by the dinoflagellate protozoan Amyloodinium ocellatum on the gills of Mugil liza, which causes the velvet disease in several fish species. These parasites produce severe lesions in the gills, with hyperplasia of primary and secondary gill lamellae rupture of pillar cells, and hyperplasia of chloride cells (ionocytes). The gill structure is totally affected, which presumably impairs normal hematosis and electrolyte regulation and seriously compromises the fish's health. The lesions caused by A. ocellatum are responsible for high mortality rates in fish farms and economic losses in the industry. In the present study, we found cellular hyperplasia of the respiratory epithelium, epithelial disruption, the collapse of secondary lamellae, and various degenerative changes that seriously compromise the gill functioning.