The constant production of solids in intensive shrimp and tilapia culture can affect the performance of macroalgae when cultivated in an integrated system, and little is known about culture structures that enhance the performance of macroalgae in biofloc systems. The objective of this work was to evaluate different depths of culture structure for the macroalgae Ulva lactuca in an integrated system with Litopenaeus vannamei and Oreochromis niloticus in a biofloc system. The experiment lasted 70 days, with six systems composed of: a 16 m³ shrimp tank, a 3 m³ tilapia tank, and a 3 m³ macroalgae tank, with water recirculation between tanks. Two treatments were carried out, shallow float, with a structural depth of 10 cm, and bottom float, where the depth was kept at 30 cm from the surface. The shallow float resulted in a growth rate of up to 0.95 ± 0.54% day⁻¹, with biomass loss only at the end of the culture due to the high density of macroalgae, decreasing temperature, and increasing solids concentration. The bottom float had biomass loss throughout the culture cycle. The integrated culture of shrimp, fish, and macroalgae is feasible with the use of shallow floats within 10 cm from the surface.

The incorporation of aquaponics into saline integrated multitrophic aquaculture (IMTA) systems, employing biofloc technology (BFT), relies on the cultivation of halophytes capable of withstanding the physical–chemical conditions created by the unique microbial communities in BFT systems. This study aimed to evaluate the integration of the halophyte Salicornia neei with tilapia (Oreochromis niloticus) and marine shrimp (Litopenaeus vannamei) reared in BFT systems dominated by chemoautotrophic (CHE) and heterotrophic (HET) microorganisms over a period of 84 days in southern Brazil. Each BFT treatment had three replicates, composed of IMTA units. The stocking densities were 400 ind. m⁻³ (17 m³ circular tanks), 44 ind. m⁻³ (4 m³ circular tanks), and 30 ind. m⁻² (4.8 m² hydroponic benches) for shrimp, fish, and halophyte, respectively. The highest S. neei individual shoot production (up to 31 g per 30 days) was observed in the CHE treatment, along with favorable agronomic characteristics, possibly due to overall elevated nitrate (98.41 mg N−NO₃ L⁻¹) and phosphate concentrations (4.62 P−PO₄ L⁻¹). Shrimp in the CHE treatment displayed higher average final weight, specific growth rate, productivity, and survival (11.24 g, 2.88% day⁻¹, 3.86 kg m⁻³, and 90%, respectively) compared to the HET treatment. Results indicated no significant difference in tilapia zootechnical performance between treatments.

The aim of this study was to evaluate the performance of Penaeus vannamei and Oreochromis niloticus in an integrated multi-trophic system with biofloc technology using different strategies. Two treatments were developed: TC (chemoautotrophic) and TH (heterotrophic). The TC treatment started 46 days before stocking the animals, with inorganic fertilization. In the TH treatment, organic fertilization was carried out after stocking the animals. Four hundred shrimp∙m-2 (1.00 ± 0.04 g) and 45 tilapia fry∙m-3 (25 ± 0.50 g) were stocked for 86 days. Water quality parameters such as temperature, oxygen, and pH were monitored daily. Total ammonia, nitrite, nitrate, phosphate, total suspended solids, and settleable solids were monitored twice a week. Prior fertilization in the chemoautotrophic treatment avoided high concentrations of nitrogen compounds in the system, due to the prior establishment of bacteria, compared to the heterotrophic treatment. The increase in nitrogen compounds in heterotrophic treatment led to higher water use, reduction in feed and consequently lower shrimp growth performance compared to the chemoautotrophic system. Tilapia’s growth was not affected. Therefore, the use of prior fertilization in chemoautotrophic treatment allowed for a higher final weight, yield of shrimp, and greater environmental sustainability.