Marcio Aquio Hoshiba

Physiological responses of piau (Leporinus friderici, Bloch 1794) to transportation

This study evaluated stress indicators of juvenile piau (Leporinus friderici) during and after a 4-hour transportation in order to establish an appropriate transportation protocol for this type of fish. Fish were transported in plastic bags (133.1 g/L) and sampled before loading, during 1, 2, 3 and 4 h and after transportation (2, 6, 12 and 24 h). Blood samples were analyzed for cortisol and glucose levels, hematocrit, hemoglobin level, number and mean corpuscular volume of erythrocytes. Water pH, dissolved oxygen, temperature and ammonia were monitored before, during and after transportation. No mortality was observed through the experiment. Ammonia levels increased throughout transportation, but the low pH values kept NH3 in safe levels for fish. Cortisol levels increased within 4 h of transportation, and returned to control condition 2 h after arrival. Plasma glucose increased within one hour of transportation, reaching peak value within 4 h and returning to initial condition 2 h after arrival. Erythrocyte number and hemoglobin levels showed the lowest levels 2 h after arrival, and mean corpuscular volume increased during transportation, decreasing at 12 and 24 h after arrival. Transporting piau is stressful, but fish recover the initial condition in short time, showing tolerance to the changes in the water quality parameters.

Óleo de cravo como anestésico para guppy

The present study evaluated different concentrations of clove oil for anesthesia of guppy (Poecilia reticulata). Adult female, male and juveniles fish were used to assess the influence of the anesthesia. The animals were individually submitted to the following clove oil concentrations: 50, 75, 100, 125 and 150 mg L-1. The induction, recovery stages and mortality 96 hours after the experiment were evaluated. All fish exposed to experimental concentrations reached the final stage of anesthesia. Adult female and male and juveniles guppies respond differently to anesthesia induction by clove oil. Thus, it is recommended the use of clove oil on concentrations of 125 mg L-1 for adult males and from 75 mg L-1 to 150 mg L-1 for adult females and juveniles animals.

Routine exposure to biometric procedures in fish farming reveals differences in stress response in tambaqui and hybrid tambatinga

The physiological stress responses of tambaqui and hybrid tambatinga were evaluated after subjecting the fish to routine practices in a breeding system such as periodic biometric procedures. For 270 days of culture, the fish underwent monthly biometric measurements, and at the end of the period, blood was collected at six sampling times (before, immediately after and 2, 24, 48 and 72 h after biometric measurements) for the evaluation of physiological indicators of stress. Tambatinga are more susceptible to stress because they presented higher levels of cortisol and glucose in the bloodstream after handling and took longer to recover their basal physiological state for these parameters. However, the low cortisol levels observed in both species suggest that the fish were familiar with biometric procedures, resulting in a less intense response. Handling led to an increase in the cellular volume of erythrocytes in tambaqui, resulting in a change in hematocrit and a decrease in hemoglobin concentration. Hypochloremia was found in both species only 72 h after handling. Biometric procedures promote hormonal, hematological and hydroelectrolytic changes in the tambaqui and hybrid tambatinga, but when routinely adopted, at regular intervals, they elicit stress responses of lower magnitude.The physiological stress responses of tambaqui and hybrid tambatinga were evaluated after subjecting the fish to routine practices in a breeding system such as periodic biometric procedures. For 270 days of culture, the fish underwent monthly biometric measurements, and, at the end of the period, blood was collected at six sampling times (before, immediately after, and 2, 24, 48 and 72 h after biometric measurements) for the evaluation of physiological indicators of stress. Tambatinga is more susceptible to stress because it presented higher levels of cortisol and glucose in the bloodstream after handling and took longer to recover its basal physiological state for these parameters. However, the low cortisol levels observed in both species suggest that the fish were familiar with biometric procedures, resulting in a less intense response. Handling led to an increase in the cellular volume of erythrocytes in tambaqui, resulting in a change in hematocrit and a decrease in hemoglobin concentration. Hypochloremia was found in both species only 72 h after handling. Biometric procedures promote hormonal, hematological and hydroelectrolytic changes in the tambaqui and hybrid tambatinga, but when routinely adopted, at regular intervals, they elicit stress responses of lower magnitude.

Fillet and carcass yield and fillet chemical composition of piava from fish farming and from the wild

Piava (Leporinus obtusidens) is one of the main cultivated native fish and one of the most caught in Rio Grande do Sul, South Brazil. The objective of this work was to compare the carcass and fillet yields of piava, females and males, collected from the wild (Treatment 1 T1) and from fish culture (Treatment 2 T2) and to analyze the chemical composition of fillets. For this purpose, four females and four males of each treatment were used. T1 females had significant higher values (P<0.05) in the carcass yield. Chemical analyses of the fillet indicated that fish originating from fish farming, independent of sex, showed higher values (P<0.05) for protein and ash contents. Thus, the management and the suitable food in fish farming could contribute to the production of a better quality fish.