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Copyright of Tanzania Journal of Health Research is the property of Tanzania Health Research User's Trust Fund and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Brazilian Journal of Biology is the property of Instituto Internacional de Ecologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This study evaluated the use of the essential oil of Lippia origanoides (EOLO) as an anesthetic for juvenile pacu, Piaractus mesopotamicus. Two experiments were performed. In Experiment I, anesthetic induction and recovery times and ventilatory frequency (VF) were determined for fish (n= 48; 29.94 ± 6.69 g) exposed to different EOLO concentrations [0 (control - 4000 µL alcohol L-1), 25, 50, 100, 200 and 400 µL L-1]. From the responses obtained in Experiment I, the EOLO concentrations of Experiment II (n= 36; 29.25 ± 5.90 g) were determined, which evaluated the effects of 0 (control - 2000 µL alcohol L-1), 50 (outside recommended induction and recovery times) and 200 µL L-1 (within recommended induction and recovery times) by analyzing immunohematological and biochemical parameters at different collection times (1 h and 24 h post-induction). Fish survival was 100% in both experiments. The EOLO concentration of 25 µL L-1 was not able to induce deep anesthesia in the animals, while the concentration of 200 µL L-1 showed induction and recovery times within the range indicated for fish and was efficient at reducing VF during induction. No differences were observed in immunohematological and biochemical parameters among concentrations, but differences were observed in comparisons between collection times. Nonetheless, blood variables returned to levels considered normal for the species in approximately 24 hours. Therefore, an EOLO concentration of 200 µL L-1 can be considered safe for use prior to biometric management of P. mesopotamicus.

Biometric evaluations are essential to determine the growth characteristics related to the weight and length of fish. This study aimed to determine the growth patterns of juvenile piraputangas (Brycon hilarii) produced in hapas within an excavated pond. The piraputangas were anesthetized and micro-chipped and their biometric characteristics were measured. Subsequently, the fish were distributed in six hapas of eight m3 at the density of 20 fish/hapa, totaling 120 animals. During the experimental period six months, the fish were fed twice (5% of the biomass) a day. Every 30 days, all fish were sampled to measure the biometric characteristics of body weight (g); standard length; total length; head height; head length; body height and body width (cm). The calculations of the weight ratio with the biometric characteristics were determined using allometric equation and estimated by linear regression according to the equation log Y = log a + b log X. All tested relationships were significant by the Student t-test (p < 0.05). Allometric growth was positive for: weight x total length; standard weight x length; weight x head height; weight x head length and weight x body height. The relative condition factor of piraputangas observed in this study was 1.00. The study provided information on the allometric parameters of juvenile Brycon hilarii produced in hapas, and the relative condition factor indicated good growth conditions for piraputangas with positive allometric growth.