Paulo César Falanghe Carneiro

Transport of jundiá Rhamdia quelen juveniles at different loading densities: water quality and blood parameters

O transporte de peixes e uma pratica comum em piscicultura e considerado como um agente estressor que causa efeitos negativos na saude do peixe. O objetivo deste estudo foi avaliar algumas respostas fisiologicas de estresse no jundia causadas pelo transporte em densidades diferentes. Juvenis de jundia foram transportados em sacos plasticos num simulador de transporte por quatro horas em diferentes densidades (75, 150, 250 e 350 g L-1) e transferidos para 16 caixas plasticas de 80 L por 96 horas apos o transporte. Amostras de agua foram coletadas antes e apos o transporte para determinacoes de oxigenio dissolvido, temperatura, pH e amonia. Alem dos momentos da saida e da chegada, amostras de sangue foram retiradas 24 e 96 horas apos o transporte para monitorar os niveis de cortisol, glicose, amonia, cloreto e hematocrito. A amonia na agua aumentou gradualmente acompanhando o aumento das densidades. A amonia plasmatica estava elevada apos o transporte nos peixes de todos os tratamentos. Comparando com os valores iniciais, aumentos substanciais nos niveis plasmaticos de cortisol e amonia foram registrados principalmente nos peixes submetidos a densidade de transporte mais elevada. Os niveis glicemicos parecem ter sido influenciados pelo aumento nas densidades de transporte. Nao foram registradas diferencas significativas nos demais parâmetros sanguineos. O custo da criacao de peixes, da mesma forma que de outros animais, deve ser minimizado e os produtores dependem de tecnicas que permitam lucros maiores. Portanto, com base nos indicadores fisiologicos e na taxa de sobrevivencia obtidos no presente estudo, especialmente considerando o periodo de recuperacao, sugere-se que a melhor densidade para o transporte do jundia em sacos plasticos por quatro horas seja de aproximadamente 350 g/L.

Standardization of European eel (Anguilla anguilla) sperm motility evaluation by CASA software

The development of powerful computer-assisted sperm analysis software has made kinetic studies of spermatozoa possible. This system has been used and validated for several species, but some technical questions have emerged regarding fish sample evaluations (i.e., frame rate, sperm dilution, chamber model, time of analysis, magnification lens, etc.). In the present study, we have evaluated the effects of different procedural and biological settings with the aim to correctly measure sperm quality parameters of the European eel. The use of different chambers did not affect the sperm motility parameters. However, regarding lens magnification, 10× was the most accurate lens, showing the least variation in the acquired data. Similarly, the frame rate setting resulted in a dramatic effect in some sperm kinetic parameters, primarily in terms of curvilinear velocity; we therefore recommend using the cameras highest available frame rate setting. Finally, the reduction in sperm motility over postactivation times suggests that sperm analysis should be performed within the first 60 seconds after activation of the European eel sperm. In conclusion, some protocol variables of sperm analysis by computer-assisted sperm analysis software can affect the measurement of eel sperm quality parameters, and should be considered before directly comparing results obtained by different laboratories. Moreover, because marine fish species show relatively similar features of sperm kinetic parameters, these results could be considered in the evaluation of the motility of sperm from other fish species.

Hormonal induction and semen characteristics of tambaqui Colossoma macropomum.

In the hatchery-bred tambaqui Colossoma macropomum, spontaneous semen release does not occur, and hand-stripping produces reduced semen volume. The goal of this work is to evaluate the effects of hormonal induction with carp pituitary extract (CPE) on both qualitative (visual aspect, pH, motility, viability and morphological abnormalities) and quantitative (volume, concentration and number of spermatozoa per ejaculate) traits of tambaqui semen. Eleven males were treated with CPE (induced), and 11 were left untreated as a control (non-induced). All analysed parameters except motility and percentage of viable spermatozoa presented significant differences (p < 0.05) between the induced and non-induced treatments. CPE induction resulted in a 25-fold increase in semen volume and a 10-fold increase in the number of spermatozoa collected. However, both sperm concentration and the frequency of sperm with morphological abnormalities (commonly detached heads or bent tails) were significantly lower in CPE-induced fish. The hormonal induction of tambaqui males with CPE is efficient and positively influences some qualitative and quantitative properties of semen. Additionally, semen collection via gentle abdominal massage occurs more readily in CPE-induced fish.

Development of the neotropical catfish Rhamdia quelen (Siluriformes, Heptapteridae) incubated in different temperature regimes

The developmental stages for the embryonic and larval periods of the silver catfish (Rhamdia quelen) kept at different temperatures (21, 24, 27 and 30 degrees C) are described. Fish were analysed under light and scanning electron microscopy. For embryonic development, we described 25 stages, which were grouped into seven periods named zygote, cleavage, blastula, gastrula, segmentation, pharyngula and hatching periods. For larval development, we defined three stages (early, mid, and late larvae). Additionally, the main ontogenetic events during the post-larvae and early juvenile periods were also described. This species presents a well developed lateral line and chemosensory systems that grow up during the larval period, maturing in the post-larvae. All tested temperatures are viable to R. quelen development, but a shorter incubation period was necessary to complete the development at lower temperatures. However, some malformations (heart edema) were verified at 30 degrees C.

Use of cryotubes for the cryopreservation of tambaqui fish semen (Colossoma macropomum).

Tambaqui (Colossoma macropomum) is a freshwater fish of great importance to aquaculture in several South American countries. Recent studies have developed a protocol for semen cryopreservation in 0.25 and 0.5 mL straws; however, this technique has limitations for fingerling production at a large scale due to the high fecundity of tambaqui. The main objective of this study was to evaluate the feasibility of using cryotubes (1.6 and 4.5 mL) for tambaqui semen cryopreservation. Semen samples were diluted in freezing solution (5% glucose solution, 10% methylglycol, 5% egg yolk), stored in 1.6 and 4.5 mL cryotubes, frozen in liquid nitrogen vapor at -175°C and transferred to a cryogenic container at -196°C. The cryotubes were thawed in a water bath at 60°C for 70 or 90 s and the motility (total motility - TM; progressive motility - PM; curvilinear velocity - VCL; straight line velocity - VSL and average path velocity - VAP) and the viability of sperm were evaluated. There was no significant difference in sperm motility and viability post-thawing between 1.6 and 4.5m L cryotubes, except for TM (47% and 40%, respectively). Thawing for 90 s provided better results, being used in fertilization trials. Although the fertilization rate did not differ between the cryotubes (41-45%), it was significantly lower than that for fresh semen (74%). A strong positive correlation was observed between the sperm motility and fertilization rate (r=0.69-0.89). We conclude that 1.6 and 4.5 mL cryotubes have high potential for tambaqui semen cryopreservation when thawed for a minimum time of 90 s at 60°C.