RESUMO INTRODUÇÃOO cultivo de Rhamdia quelen (jundiá) está aumentando no sul do Brasil, mas ainda está muito abaixo de suas possibilidades, pois vários parâmetros biológicos sobre a espécie estão faltando ou dispersos na literatura. Portanto, o objetivo deste trabalho é revisar os dados existentes sobre a biologia de R. quelen e indicar futuros estudos que possam auxiliar no cultivo dessa espécie.

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This study investigated the effectiveness of eugenol and of the essential oil (EO) of Lippia alba when used in the transport of the silver catfish (Rhamdia quelen). These investigations involved measurements of blood (pH, PvO(2), PvCO(2) and HCO(3) (-)) and water parameters, survival and ionoregulatory balance. Fish (301.24 ± 21.40 g, 28.90 ± 1.30 cm) were transported at a loading density of 169.2 g L(-1) for 4 h in fifteen plastic bags (7 L) divided into five treatments: control, 1.5 or 3.0 μL L(-1) of eugenol and 10 or 20 μL L(-1) of EO of L. alba. The water parameters were measured before (0 h) and after (4 h) transportation. The net Na(+), Cl(-) and K(+) losses were higher in fish from the control treatment compared to the other treatments. The PvO(2), PvCO(2) and HCO(3) (-) increased significantly in all of the treatments at the end of the transport period. In conclusion, based on the water (total ammonia nitrogen) and ionoregulatory indicators determined in the present study, our findings indicate that eugenol and the EO of L. alba are recommended for use in the transport of this species because these anesthetics apparently reduce stress.

This study investigated the efficacy of the essential oil (EO) of Aloysia triphylla as an anesthetic for albino and gray strains of silver catfish, Rhamdia quelen. Juveniles were exposed to concentrations between 20 and 800 μL L(-1) EO of A. triphylla to evaluate time of induction and recovery from anesthesia. In another experiment, both strains were divided into four groups such as 0 (control), 30, 40, or 50 μL L(-1) EO and transported for 5 h. The longest time for anesthetic induction and recovery was observed in the albinos. Both strains reached anesthesia in the 100-800 μL L(-1) (11.1-1.24 min) range, without mortality, being 200 μL L(-1) the best response considering time to anesthesia (5.35 min). Albinos transported with all EO concentrations showed higher values of carbon dioxide in the water of transport, but lower levels were observed in grays transported with 40 and 50 μL L(-1) EO when compared to control fish. The same concentrations did not prevent significant whole-body cortisol rise at the end of transport in the albino strain. Juveniles of both strains transported with EO presented lower ion loss to the water compared to control fish. The EO of A. triphylla is an effective anesthetic for albino and gray silver catfish. This EO increases whole-body cortisol levels in the albino strain, but as it reduces net ion loss as in the gray strain, it can be also recommended for transport.

Nutritional strategies focused on the use of phytochemicals as modulators of immunological and physiological responses, as well as antistress and antioxidant therapies and health promoters of the gastrointestinal tract have attracted increased interest in animal production. Over the past two decades, several studies have reported positive results of using plant essential oils (EOs) as dietary additive in several farm animal species. Recently, these nutritional alternatives have been evaluated and reported in fish production in order to enhance the resistance to diseases and prevent outbreaks, as well as to improve fish growth, animal welfare and feed utilization. However, despite the diverse and relevant biological activities reported, these phytochemicals are composed of often unstable and volatile molecules, which makes the chemical and physical characteristics of the EOs important aspects to be considered in fish nutrition research. This review summarizes the current knowledge regarding the use of plant EOs as fish dietary additives, focusing on their potential as modulators of the gut bacterial community and discussing some aspects regarding their stability in feeds.

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The aim of this study was to evaluate the anesthesia induction and recovery times of sub-adult and post-larvae white shrimp (Litopenaeus vannamei) that were treated with eugenol and the essential oils (EOs) from Lippia alba and Aloysia triphylla. Oxidative stress parameters in the hemolymph of this species were also analyzed. The concentrations of eugenol, A. triphylla EO and L. alba EO recommended for anesthesia were 200, 300 and 750 μL L(-1) for sub-adults and 175, 300 and 500 μL L(-1) for post-larvae, respectively. The concentrations studied during the transport of sub-adults were between 20 and 50 μL L(-1) eugenol, 20-30 μL L(-1)A. triphylla EO and 50 μL L(-1)L. alba EO. For post-larvae, the optimal concentrations for transport were 20 μL L(-1) eugenol and between 20 and 50 μL L(-1)A. triphylla EO. The white shrimp sub-adults that were exposed to A. triphylla EO (20 μL L(-1)) showed increases in their total antioxidant capacities (150%), catalase (70%) and glutathione-S-transferase (615%) activity after 6 h. L. alba EO (50 μL L(-1)) and eugenol (20 μL L(-1)) also increased GST activity (1292 and 1315%) after 6 h, and eugenol (20 μL L(-1)) decreased the total antioxidant capacity (100%). Moreover, concentrations above 30 μL L(-1) for the EOs of A. triphylla and L. alba and 20 μL L(-1) eugenol were effective at inducing anesthesia and improving the antioxidant system against reactive oxygen species (ROS) after 6 h.

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