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This study evaluated the potential of alternative treatments against larval stages of Lernaea cypriancea. For in vitro test, the nanoemulsified oils of Pinus sp. acicule and resin were evaluated, along with Biogermex® (commercial product based on citrus biomass). For this, the motility of five larvae of the same stage (nauplii or copepodite) were evaluated in a 96-well microplate. Using the best results, on the in vivo test, fries of Rhamdia quelen were submitted to a long-term immersion bath (96 h) containing different concentrations of the product diluted directly in the water. It was possible to notice the antiparasitic potential of the resin and the acicule of Pinus sp., as well as the citrus biomass extract against the parasites. The nanoemulsified oils successfully inhibited the development of nauplii (10 mg L− 1 in 24 h) and the fries showed to be tolerant to the presence of the compound (LC50 96h − 16.74 mg L− 1). The concentration of 30.5 mg L− 1 of Biogermex® eliminated the copepodites within 24 h, being more efficient than Pinus sp. when tested at the same stage, at the times analyzed. The results obtained indicate a potential use of these compounds as prophylactic agents against L. cyprinacea.

The study analyzed the hematoimmunological effects of the joint dietary supplementation of immunomodulators (β-glucans-nucleotides) and different levels of vitamins for Nile tilapia after physical and acute stress. Four treatments with different experimental diets were used: diets with indicated vitamin levels (Vit ind); Vit ind + 0.5% immunomodulator (Vit ind+Immune); rations with a high level of vitamins (Vit high); Vit high + 0.5% immunomodulator (Vit high+Immune). The experiment included 560 fish (3.0 ± 0.68 g of initial weight and 5.33 ± 0.66 cm of initial length), in 28 tanks and 25 fish/tank, with 7 replicates. After 60 days of supplementation, the animals had a weight of 33.30 ± 7.6 g and a length of 11.97 ± 0.94 cm. The water temperature was set at 20°C and two complete biometrics were performed. Subsequently, the animals were conditioned to two stress factors: physical (I), temperature oscillations: 20ºC to 30ºC/30ºC to 20ºC/20ºC to 30ºC; (II), the same animals were placed in plastic bags with dechlorinated water and shaken for 5 minutes and returned to their respective tanks. For hematoimmunological data, 140 animals were used after stress. Antimicrobial title and total plasma protein were significantly higher in fish that did not receive an immunomodulator. Differently, the binder title increased in fish fed with lower levels of vitamins, while immunoglobulin showed immunomodulatory interaction x level of vitamins. In summary, the inclusion of immunomodulators increased the animals' resistance to physical and acute stress, and improved hematoimmunological parameters, and the high level of vitamins did not modulate immune responses.