This study evaluated the use of therapeutic baths containing essential oils of Lippia sidoides (pepper rosemary) and Mentha piperita (peppermint) on the hematological parameters of Nile tilapia parasitized by the monogeneans Cichlidogyrus tilapiae, Cichlidogyrus thurstonae, Cichlidogyrus halli, and Scutogyrus longicornis. A total of 320 juvenile fish were distributed into 16 tanks of capacity 100 L (20 fish per tank), divided into 4 treatments in quadruplicates: fish exposed to a bath of L. sidoides at 20 mg L −1 ; fish exposed to M. piperita at 40 mg L −1 ; fish exposed only to a water bath; and fish exposed to water + DMSO (dimethyl sulfoxide) bath. The fish were subjected to 3 baths for 10 min, at intervals of 24 h between treatments. After the third bath, parasitological and hematological analyses were performed. The parasite prevalence in fish treated with essential oils was seen to have decreased by 70%. The efficacy attained among fish treated with L. sidoides, in comparison with control water and water + DMSO, was 1.96% and 14.16%, respectively; and among fish treated with M. piperita, it was 33.33% and 41.63%, respectively. The total numbers of red blood cells (RBC) and thrombocytes were lower in fish treated with L. sidoides. Glucose concentration and neutrophil count were significantly higher in fish treated with L. sidoides. Because of the efficacy and positive hematological results, we suggest that baths of M. piperita at 40 mg L −1 should be used as anthelmintic action. Statement of relevance: Authors believe on the use of essential oils to treat ectoparasites of cultured fish and consequently no damages for hematological profile of Nile tilapia were found.

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RESUMO:O objetivo deste estudo foi avaliar o efeito de níveis de proteína digestível -PD na dieta sobre o desempenho do acará-bandeira (Pterophyllum scalare). O delineamento foi inteiramente casualizado, composto por cinco tratamentos (30, 32, 34, 36 e 38% de PD) e quatro repetições, durante 60 dias. Foram utilizados 200 peixes, distribuídos em 20 aquários de 45l cada, em sistema de recirculação, com temperatura controlada e fotoperíodo de 12h. Os animais foram submetidos a uma dieta isoenergética 3200 Kcal.kg-1 de energia digestível e, contendo níveis crescentes de PD. Foram analisados os índices zootécnicos levando em consideração: ganho de peso, conversão alimentar aparente, taxa de eficiência proteica, taxa de crescimento específico e conversão alimentar aparente. Os resultados foram submetidos à análise de variância (ANOVA), seguida pelo teste de Tukey (P<0,05) e análise de regressão. Na avaliação dos índices zootécnicos, os animais alimentados com a dieta contendo 32% de PD apresentaram desempenho inferior aos demais. Os valores de 34%, 36% e 38% de PD não diferiram entre si (P>0,05). Dessa forma, conclui-se que juvenis de acará-bandeira podem ser alimentados com 34% de PD sem comprometer o desempenho zootécnico, considerando o elevado custo associado à inclusão de proteína a níveis superiores. Palavras-chave: desempenho produtivo; nutrição; peixes ornamentais ABSTRACT: The aim of this study was to evaluate the effect of levels of digestible protein -DP in the diet on the performance of the Angelfish (Pterophyllum scalare). The design was completely randomized, consisting of five treatments (30%, 32%, 34%, 36% and 38% of DP) and four replications for 60 days. Two hundred fish were distributed in 20 tanks of 45 liters each in a recirculation system with controlled temperature and photoperiod of 12h (light / dark). The zootechnical indexes were analyzed taking into consideration: weight gain, feed conversion, protein efficiency rate, specific growth rate and apparent feed conversion. The results were submitted to analysis of variance (ANOVA), followed by the Tukey test (P<0.05) and regression analysis. In the evaluation of the zootechnical indexes, the animals fed a diet containing 32% of DP presented inferior performance to the others. The values of 34%, 36% and 38% of DP did not differ from each other (P>0.05). Thus, it can be concluded that the juvenile angelfish can be fed with 34% PD without compromising the zootechnical performance, considering the high cost associated with the inclusion of protein at higher levels.