Walisson de Souza e Silva

This study evaluated the anesthetic efficacy of eugenol for two size classes of Aulonocara nyassae and Aulonocara stuartgranti. The experimental groups were classified as follows: A. nyassae, Juvenile I-Any (1.29 ± 0.35 g) and Juvenile II-Any (2.97 ± 0.67 g); and A. stuartgranti, Juvenile I-Ast (1.98 ± 0.60 g) and Juvenile II-Ast (3.69 ± 0.74 g). For each group, 80 specimens were randomly allocated to seven eugenol concentrations (25, 50, 75, 100, 125, 150 and 175 mg L-1) and a control (ethanol) in a completely randomized design with 10 individuals per concentration. Anesthesia trials involved exposing one animal at a time to the different eugenol concentrations, and recording induction time, recovery time, but ventilatory frequency was also measured during induction and recovery. The efficacy of an anesthetic administered via immersion bath is related to rapid induction to deep anesthesia (<180 s) and short recovery (<300 s). Therefore, the study demonstrated that eugenol concentrations between 50 and 175 mg L-1 are recommended for Juvenile I-Any and between 25 and 175 mg L-1 for Juvenile II-Any. The ideal concentrations for A. stuartgranti, on the other hand, range from 25 to 175 mg L-1 for both evaluated size classes.

This study assessed the growth, gonadal development, first maturation, sperm quality, and first reproduction of Colossoma macropomum raised under controlled conditions. The animals were maintained under consistent conditions. The mean weights reached after the first, second, and third years were 0.94 kg (0.50–1.42 kg), 3.78 kg (3.02–5.19 kg), and 5.66 kg (3.88–8.17 kg), respectively. The highest biomass was 14.1 kg/m³ at 890 days after hatching (DAH), while at the end of the study it was 5.6 kg/m³. Feed conversion remained below 2.0. No differences in weight or length were observed between males and females of the same age. Of the three males analyzed at 590 DAH, one was at rest and two were in initial maturation. Advanced male maturation was first recorded at 710 DAH. Six females showed initial maturation at 710 DAH, while advanced female maturation was first recorded at 890 DAH. Data on VFI, HSI, and GSI throughout development are presented. Sperm quality parameters did not differ between males at 890 and those at 990 DAH. Two out of four induced females spawned. This study is the first to provide evidence suggesting that the life cycle of C. macropomum can be completed in RAS.

To evaluate hematological and biochemical parameters after testing in a new environment, and the zootechnical performance of Oreochromis niloticus classified as proactive or reactive. In experiment 1, male Nile tilapia with an average weight of 128.33 ± 34.17 g were kept in a recirculating aquaculture system (RAS). Immediately after classification, blood samples were collected from 20 reactive and 20 proactive animals. In experiment 2, 60 proactive and 60 reactive males were classified, with an average weight of 88.23 ± 21.59 g, which were divided into the following treatments: PT (40 proactive animals), RT (40 reactive) MT (20 proactive + 20 reactive ). Animals were fed twice daily for 90 days. In experiment 1, reactive animals had higher amounts of hemoglobin and cortisol and lower amounts of leukocytes detected. In experiment 2, weight gain was greater in proactive animals (PT) and reactive animals (RT); however, the best feed conversion was obtained in reactive animals. The survival rate was lower in the MT treatment group of animals. Hemoglobin and glucose had lower values for proactive animals and for those that were mixed, in the MT group. Cholesterol was higher in animals PT. It is concluded that variables such as hemoglobin, cortisol, leukocytes and cholesterol are more likely to undergo changes between personality traits. Furthermore, it can be concluded that reactive and proactive O. niloticus, grown in separate environments, have the same potential for weight gain; however, the food conversion of reactive ones is better.

This study evaluated the use of essential oil of Ocimum gratissimum (EOOG) for anesthesia and in transport of Colossoma macropomum. Experiment 1, Test 1, anesthesia induction and recovery times were determined using different EOOG concentrations (0, 20, 50, 100, 200, 300 mg L⁻¹), with two size classes: Juveniles I (0.86 g) and Juveniles II (11.46 g) (independent tests in a completely randomized design). Based on the results of Test 1, in Test 2 Juveniles II were exposed to EOOG concentrations: 0, 20, 100 mg L⁻¹. Tissue samples were collected immediately after induction and 1 h post-recovery, to assess oxidative status variables. Experiment 2, Juveniles I (0.91 g) and Juveniles II (14.76 g) were submitted to transport in water with different concentrations of EOOG (0, 5, 10 mg L⁻¹) (independent tests in a completely randomized design). The effects on oxidative status variables were evaluated. Concentrations between 50 and 200 mg L⁻¹ EOOG can be indicated for Juveniles I, while concentrations between 50 and 100 mg L⁻¹ EOOG for Juveniles II. The concentration of 100 mg L⁻¹ EOOG was able to prevent oxidative damage in the liver. In Experiment 2, the concentrations of 5 and 10 mg L⁻¹ EOOG added to the transport water caused sedation for both studied size classes of juveniles and did not cause oscillations in water quality variables nor any mortality. The concentration of 10 mg L⁻¹ EOOG improved the oxidative status. It can be concluded that EOOG can be used for anesthesia and transport of C. macropomum.

POSITIVE CRITIQUE: Relevance and Significance: The article addresses a pressing environmental issue concerning cadmium contamination in freshwater ecosystems, particularly its impact on fish species such as Channa punctatus. By focusing on a commerc...

The aim of the study was to evaluate survival and water quality during the transport of Hypsolebias flagellatus using different concentrations of salt in water and different transport times in association with different previous diets. In experiment I, 40 males (1.38 ± 0.83 g) were used and the tested salinities were: 0 (control), 2, 4 and 6 g of salt/L. Dissolved oxygen was the highest in the concentration of 4 g of salt/L and lower in the control treatment (P <.05). In experiment II, 30 males fed (0.68 ± 0.27 g) with commercial diet and 30 males (1.48 ± 1.00 g) fed with artemia were transported during 12, 24 and 48 hours. The survival after transport was lower in 48 hours (P <.05). The water pH was higher in animals fed with diet (P <.05). The water temperature and water total ammonia increased with increasing transport time (P <.05). Dissolved oxygen decreases regardless of diet (P <.05).

Biochemical parameters of fish are important indicators of homeostasis as they represent an organism's response to the environment. Lophiosilurus alexandri is an endemic and endangered species of the São Francisco River in Brazil with potential for aquaculture; however, blood biochemical studies of this species are scarce. The present study compared blood biochemical parameters of male and female L. alexandri, at four different ages. The following analytes were evaluated: alanine aminotransferase (ALT), aspartate transaminase (AST), lactate dehydrogenase (LDH), calcium, chlorine, magnesium, total proteins, albumin, urea, glucose, triglycerides and cholesterol. Male fish had higher values than females for ALT at 372 days after hatching (DAH), magnesium at 481 DAH and triglycerides at 372 and 481 DAH (p < 0.05). The other analytes did not differ significantly (p > 0.05) between males and females at any of the collection times. The results allow us to conclude that biochemical differences between males and females are less pronounced than those observed among different ages of the same sex.