Deltamethrin-induced nuclear erythrocyte alteration and damage to the gills and liver of Colossoma macropomum.

Deltamethrin is one of the most commonly used pyrethroids in the world, and it has a high toxic potential, mainly on aquatic organism. Thus, the purpose of this study was to evaluate LC50 values of deltamethrin on tambaqui (Colossoma macropomum) fingerlings and to investigate genotoxic effects and histopathological responses. Fish were exposed to different concentrations of deltamethrin (0, 6.16 × 10-3; 6.44 × 10-2; 1.34 × 10-1, and 1.93 × 10-1 mg L-1) for 96 h. In addition, a genotoxicity analysis was carried out on peripheral blood erythrocytes and histopathological changes were classified by the severity degree of damage and organ functioning. The 96 h LC50 value for tambaqui was estimated at 5.56 × 10-2 mg L-1 using a static test system. Nuclear abnormalities in exposed fish included micronuclei, blebbed, notched, 8-shaped, and binucleated nuclei forms. Deltamethrin significantly induced a notched nucleus compared to other abnormalities. A histopathological examination showed hepatic lesions and gill damage. Deltamethrin was found to be highly toxic; it induced genotoxicity and caused liver and gill inflammation in tambaqui.

The effects of gelatin supplementation prior to cooling on ram semen quality and fertility.

The physical and chemical characteristics of gelatin have been used to justify its inclusion in extenders to preserve the sperm quality and improve results of cervical artificial insemination with cooled semen. The objective of this study was to evaluate the effects of gelatin supplementation in cooling extender on the quality and fertility of ram semen stored at 5°C. Semen samples (n = 24) of Santa Inês rams (n = 6) were diluted in Glycine-Yolk-Milk extender without (control) or with 1.5% of gelatin. The samples were loaded into 0.25 mL straws, cooled to 5°C and stored vertically for 48 and 72 hours. Sample quality was evaluated using straw homogeneity tests based on pH, osmolality and the proportion of spermatozoa (PS) in both upper and lower segments of straws (US and LS), analyses of sperm motility, plasma and acrosomal membrane integrity, and by fertility after artificial insemination. Differences between the US and LS of straws were found for pH and PS (%). They were significant only in the control group at both times: pH - 5.96 vs. 5.71 at 48 h and 6.13 vs. 5.89 at 72 h; PS - 21.66 vs. 78.34 at 48 h and 20.87 vs. 79.13 at 72 h. Storage in gelatin had very little, to no effect on the sperm kinetics or on the sperm membrane integrity evaluations. The addition of gelatin to the extender did not affect the pregnancy rate which ranged from 4.4 to 26.1%. We conclude that gelatin is effective in maintaining the physical and chemical homogeneity of the semen samples. Further research is needed in order to optimize the use of gelatin supplementation and elucidate any potential benefits.

Essential oils of Varronia curassavica accessions have different activity against white spot disease in freshwater fish.

The aim of this study was to evaluate the antiprotozoal activity of essential oils from Varronia curassavica accessions against different stages of Ichthyophthirius multifiliis. Essential oils from each accession were tested in vitro at the concentrations 0, 10, 25, 50, 75, 100, and 200 mg/L. The VCUR-001, VCUR-202, VCUR-509, and VCUR-601 accessions presented the major compounds α-pinene, germacrene D-4-ol, (E)-caryophyllene and epiglobulol, and sabinene, respectively. These isolated compounds were tested in vitro at a concentration proportional to that found in the essential oil which caused 100% mortality of the parasite. The concentrations of 10 and 50 mg/L of the essential oil of accession VCUR-202 provided 100% mortality of trophonts and tomonts, respectively. For the accession VCUR-509, 100% mortality of trophonts and tomonts was observed at concentrations 75 and 200 mg/L of essential oil, respectively. The same mortality was observed at concentration 200 mg/L in both stages of the parasite for the other accessions. The major compounds α-pinene, sabinene, and the (E)-caryophyllene + epiglobulol mixture caused 100% mortality of trophonts and tomonts. The in vivo assay for white spot disease control was performed in a therapeutic bath of 1 h with the essential oil of accession VCUR-202 at concentrations of 0.5 and 2.0 mg/L. A significant reduction of about 30% of trophonts on infected fish was observed, independent of the oil concentration. The V. curassavica essential oil, especially the VCUR-202 accession, is a potential source of raw material for the formulation and commercialization of bioproducts to control freshwater white spot disease in fish.

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.

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.

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

Fish transportation is a common practice on fish farms and is considered to be a stressor that could negatively affect fish health. The objective of this study was to evaluate several physiological responses of stress in jundiá caused by transport at different loading densities. Jundiá juveniles were placed in plastic bags on a mechanical transport simulator for four hours at four different loading densities (75, 150, 250 and 350 g L-1) and then transferred to sixteen 80-L plastic boxes for 96 hours after transport. Water samples were collected before and after transport to measure dissolved oxygen, temperature, pH and ammonia levels. Blood samples were taken at departure and arrival, as well as at 24 and 96 hours after transport to monitor cortisol, glucose, ammonia, chloride and hematocrit levels. Water ammonia levels were found to increase gradually as loading densities increased. Plasma ammonia was higher after transport in fish from all treatments. Compared to initial values, substantial increases in plasma cortisol and ammonia levels were detected mainly in those fish submitted to the highest loading density. Blood glucose appeared to be positively influenced by the increase of transport densities. No statistical differences were observed in any of the other blood parameters. The costs in fish culture, as in other animal production systems, must be minimized and fish producers depend on optimal techniques to ensure better profit. Therefore, based on fish survival and the physiological indicators determined in the present study, especially during recovery, the best density at which to transport jundiá in plastic bags for four hours is about 350 g/L.

O transporte de peixes é uma prática comum em piscicultura e considerado como um agente estressor que causa efeitos negativos na saúde do peixe. O objetivo deste estudo foi avaliar algumas respostas fisiológicas de estresse no jundiá causadas pelo transporte em densidades diferentes. Juvenis de jundiá foram transportados em sacos plásticos num simulador de transporte por quatro horas em diferentes densidades (75, 150, 250 e 350 g L-1) e transferidos para 16 caixas plásticas de 80 L por 96 horas após o transporte. Amostras de água foram coletadas antes e após o transporte para determinações de oxigênio dissolvido, temperatura, pH e amônia. Além dos momentos da saída e da chegada, amostras de sangue foram retiradas 24 e 96 horas após o transporte para monitorar os níveis de cortisol, glicose, amônia, cloreto e hematócrito. A amônia na água aumentou gradualmente acompanhando o aumento das densidades. A amônia plasmática estava elevada após o transporte nos peixes de todos os tratamentos. Comparando com os valores iniciais, aumentos substanciais nos níveis plasmáticos de cortisol e amônia foram registrados principalmente nos peixes submetidos à densidade de transporte mais elevada. Os níveis glicêmicos parecem ter sido influenciados pelo aumento nas densidades de transporte. Não foram registradas diferenças significativas nos demais parâmetros sanguíneos. O custo da criação de peixes, da mesma forma que de outros animais, deve ser minimizado e os produtores dependem de técnicas que permitam lucros maiores. Portanto, com base nos indicadores fisiológicos e na taxa de sobrevivência obtidos no presente estudo, especialmente considerando o período de recuperação, sugere-se que a melhor densidade para o transporte do jundiá em sacos plásticos por quatro horas seja de aproximadamente 350 g/L.

Sodium chloride added to transport water and physiological responses of Matrinxã BryconAdição de cloreto de sódio à água de transporte e respostas fisiológicas do matrinxã Brycon amazonicus(Teleost: Characidae)

A adição de sal à água tem sido utilizada para a mitigação de estresse e aumento da taxa de sobrevivência em peixes. O presente estudo avaliou o efeito do cloreto de sódio (0,0; 1,0; 3,0 e 6.0 g/l) nas concentrações de cortisol plasmático, glicemia, triglicerídios, proteínas total plasmática, hematócrito, hemoglobina, número de eritrócitos, glicogênio e lipídio hepáticos, e lipídio muscular em matrinxã Brycon amazonicum adultos após quatro horas de transporte e durante período de recuperação de 96 h. Amostras foram coletadas antes e depois do transporte, bem como 24 e 96 h após a chegada. O nível de cortisol plasmático estava mais elevado logo após o transporte quando comparado à condição inicial (pré-transporte), exceto para os peixes transportados com sal nas concentrações 3,0 e 6,0 g/l. Comportamento semelhante foi observado para a glicemia, porém os peixes dos tratamentos 0,0, 1,0 e 3,0 g/l necessitaram de período superior a 24 h para recuperar a condição inicial. Foram registrados níveis mais baixos de glicogênio hepático em peixes do tratamento controle (0,0 g/l). Os parâmetros hemoglobina, número de eritrócitos, proteína plasmática total e lipídio hepático não apresentaram alterações durante o período experimental. Os valores de hematócrito diminuíram logo após o transporte em todos os tratamentos, retornando aos níveis iniciais após 24 h. Todos os tratamentos apresentaram redução nos níveis de lipídio muscular e triglicerídios durante o período de recuperação. Os resultados sugerem que a adição de 6,0 g/l de sal na água de transporte reduz as alterações fisiológicas de estresse e que é necessário período de 96 h após o transporte para a recuperação da condição inicial de matrinxãs transportados sem a adição de sal.

The addition of salt to the water has been used to mitigate stress and improve survival in fishes. This study investigated the effects of sodium chloride (0.0, 1.0, 3.0 and 6.0 g/l) on levels of plasma cortisol, glucose, tryacilglycerol, total protein, hematocrit, hemoglobin, erythrocyte number, liver glycogen and lipid, and muscle lipid in adult matrinxã(Brycon amazonicum) after a 4-h transport and during a 96-h recovery period. Fish were sampled before and after transport, and 24 and 96 h of the recovery period. Plasma cortisol was higher than initial condition immediately after transportation, except in fish transported in 3.0 and 6.0 g/l of salt. A similar pattern was observed for blood glucose but fish transported in water with 0.0, 1.0 and 3.0 g/l of salt needed more than 24 h to return to the initial condition. Liver glycogen was lower after transport in fish not exposed to salt. Hemoglobin, erythrocyte number, total plasma protein and liver lipid did not change during the experiment but hematocrit was lower after transport in all treatments and returned to pre-transport values in 24 h. Reductions of muscle lipid and plasma tryacilglycerol were observed during the recovery period in fish from all treatments. The results show that 6.0 g/l NaCl added to the transport water reduce the stress responses and a 96-h recovery period is needed if no salt is used to mitigate the stress.

Freqüência alimentar e crescimento de alevinos de jundiá, Rhamdia quelen / Feeding frequency and growth of silver catfish, Rhamdia quelen, fingerlings

O jundiá, Rhamdia quelen, é uma espécie de peixe nativa ainda pouco conhecida cientificamente, mas que tem atraído a atenção de produtores e pesquisadores devido a várias características favoráveis à sua inclusão na lista de peixes criados comercialmente no país. A freqüência alimentar é um fator importante dentro do manejo em piscicultura visando melhorar a eficiência produtiva e reduzir os custos de produção. O presente trabalho testou quatro regimes de arraçoamento (1, 2, 3 e 4 vezes ao dia) em intervalos regulares. Alevinos de jundiá (1,88g) foram estocados em 12 tanques de 4m² por 65 dias. A temperatura da água variou de 23 a 27ºC, durante o período experimental, e os peixes de todos os tratamentos apresentaram índices zootécnicos de desempenho (ganho de peso, conversão alimentar e crescimento especifico) semelhantes. Os peixes alimentados apenas uma vez ao dia tiveram crescimento semelhante àqueles alimentados duas a quatro vezes ao dia. Estes resultados contribuem para a otimização dos recursos necessários à produção comercial do jundiá em cativeiro.