This study aimed to evaluate the growth of Arthrospira (Spirulina) platensis cultivated in Zarrouk culture medium and effluent from Nile tilapia (Oreochromis niloticus) reared in biofloc system. Four treatments were used: Control (100% Zarrouk), E50 (50% Zarrouk + 50% Tilapia effluent), E75 (25% Zarrouk + 75% Tilapia effluent), and E100 (100% Tilapia effluent), and the experiment lasted 10 days. Growth parameters such as maximum cell density (MCD), doubling time (DT), and growth rate (K) were daily evaluated, as well as pH and water temperature. In addition, the concentrations of total ammonia nitrogen (TAN), nitrite-N (NO₂-N), and nitrate-N (NO₃-N) were analyzed in order to compare nitrogen absorption. Among treatments, E50 and E75 obtained higher maximum cell densities and presented an exponential growth rate similar to the control treatment. Regarding the concentrations of nitrogen compounds, a significant reduction was observed in all treatments, with an NO₃-N uptake of 99%, followed by 80% of TAN and 90% of NO₂-N. Thus, giving the results obtained, besides being able to grow in wastewater, A. platensis can also be used in bioremediation processes, confirming the potential of this species.

The growing need for sustainable protein sources in aquaculture has led to interest in microalgae, such as Chlorella vulgaris, known for its high nutritional value. One promising strategy for delivering these nutrients is through bioencapsulation in Daphnia magna, a common live feed used in aquaculture. This study evaluated the effect of including D. magna bioencapsulated with C. vulgaris as live feed for marine shrimp Penaeus vannamei post-larvae. Shrimp were fed at two D. magna densities (5 and 10 per shrimp, 5DF and 10DF), offered weekly, and compared with a control group receiving only commercial feed (F) for 36 days in a synbiotic nursery system. Water quality, zootechnical performance, protein, and lipid content of the shrimp were analyzed using correlation analyses, nonlinear prediction models, and principal component analysis (PCA). Shrimp fed with the 10DF treatment exhibited superior zootechnical performance, characterized by a lower feed conversion ratio (1.01) and higher feed efficiency (99.97%), protein (70.91%), and lipid (32.45%) content in comparison with the 5DF and control. Quadratic regression predictive models indicated the possibility of further testing higher concentrations of D. magna per shrimp. The results indicates that the use of C. vulgaris bioencapsulated in D. magna as live feed for P. vannamei is a promising approach to improve shrimp diets and increase production in aquaculture.

This study evaluated the effects of astaxanthin from Haematococcus pluvialis on coloration, antioxidant activity, and growth performance in Cryptocentrus cinctus. Three dietary treatments were formulated with increasing astaxanthin concentrations: A0 (0%—control), A10 (0.01% of the total dry diet), and A15 (0.015% of the total dry diet). Astaxanthin supplementation significantly enhanced skin pigmentation, with A15 fish exhibiting a distinct yellow coloration (R = 144.75; G = 122.9; B = 48.5). Catalase activity was also the highest in the A15 group (25 UCAT mg-1), suggesting improved antioxidant capacity. Zootechnical performance improved with astaxanthin inclusion, as A15 fish demonstrated greater weight gain (0.44 g), length gain (7.93 mm), and a lower feed conversion ratio (1.10). Overall, dietary supplementation with 0.015% astaxanthin from H. pluvialis enhanced pigmentation, antioxidant response, and growth efficiency in C. cinctus, representing the first report of carotenoid supplementation for this species.