Spermatozoal morphology and ultrastructure of channel catfish, <i>Ictalurus punctatus</i>

The morphology, dimensions, aberrations, and ultrastructure of channel catfish (Ictalurus punctatus) spermatozoa were studied. Spermatozoa of a wild catfish stock from Louisiana were compared to those of a domestic stock from Mississippi. The spermatozoon of channel catfish consists of a rounded dark head, a collar-like midpiece, and a long flagellum. The average dimensions were: head length, 2.3 µm; midpiece length, 1.6 µm; midpiece width, 3.1 µm; and flagellum length, 94.9 µm. The flagellum had the classical (2.9 + 2) axoneme. On the average, 4.7% of the spermatozoa in the fish studied were biflagellar. Each flagellum arose from an individual centriolar complex. Domestic fish stock had a higher percentage of normal gametes compared to wild stock

Testicular and spermatozoal characteristics of channel catfish, <i>Ictalurus punctatus</i>, outside the spawning season

Several testicular and spermatological parameters of 48 male channel catfish, Ictalurus punctatus (Rafinesque) were studied during 6 months (November through April) outside the spawning season. Two stocks (a domestic and a wild one) and within each stock 2- and 3-year-old fish were compared. Within age-groups, the domestic fish were considerably larger than the wild ones. In each stock, the 3-year-olds outgrew the 2-year-olds. The testes consisted of a white spermatogenic and pink glandular part, averaging 1.14 and 0.56 g respectively. A significant increase in both parts was noticed in March, continuing during April. One 3-year-old male in each stock was azoospermic, even though these fish had well developed testes and exhibited secondary sexual characteristics. Viable sperm was present in every month at an average rate of 73.2% of the spermatozoa. The majority was in progressive motion with some vibrating in loco. The gonosomatic index averaged only 0.22% and reached a peak value of 0.32% in April. The mean gonadal sperm concentration was 5.5 x 109 spermatozoa/g wet testicular tissue and a maximum of 7.4 x 109 occurred in April. Both stocks produced a similar number of spermatozoa/g. As a group, however, the testes of the older fish contained twice as many gametes per g as those of the 2-year-olds. A highly significant (p<0.01) correlation of 0.51 existed between the width of the head (a male secondary sexual characteristic) and the gonadal sperm concentration. No pronounced differences between domestic and wild stocks were observed for most variables, but some size and/or age effects occurred

Stress responses of juvenile matrinxã (Brycon amazonicus) after transport in a closed system under different loading densities Respostas de estresse de matrinxã (Brycon amazonicus) juvenil após transporte em sistema fechado sob diferentes densidades de carga

Optimum loading density for the transport of matrinxã juveniles was investigated in a closed system with plastic bags. Transport was conducted for 4 h with fish (23.5&plusmn; 0.4g and 11.6 (0.08cm) starved for 24h at loading densities of 83g L-1 (D1), 125g L-1 (D2), 168g L-1 (D3) and 206g L-1 (D4). Fish were sampled before transport (BT), after transport (AT) and 24h AT. The water quality was monitored before capturing fish in depuration tanks, after transport in plastic bags and in recovery tanks. Water oxygen decreased to values below 4mg L-1 in D2, D3 and D4, temperature was around 32&deg;C, pH 6.5-6.78, total ammonia 1.09-1.7mg L-1, un-ionized ammonia 3.58-9.33x10³mg L-1 and alkalinity 134-165mg CaCO3 L-1. Blood cortisol and glucose concentrations increased in fish of all densities AT and recovered the BT levels 24h after arrival. Osmolality did not change AT but increased 24h AT in fish of all densities whereas plasma chloride decreased inversely to the loading densities after the procedure. Hematocrit decreased 24h AT in fish of all densities but no differences were verified in the number of erythrocytes. No mortality was registered in any treatment during the next week after transport. Matrinxã demonstrated to be a crowding tolerant-species in transport operations besides tolerating low levels of oxygen in the water.<br>Neste estudo, foram investigadas as densidades de carga adequadas para transporte de matrinxãs juvenis em sistema fechado com sacos plásticos. O transporte de 4h foi feito com peixes (23,5&plusmn;0,4g; 11,6 (0,08cm) em jejum por 24h, em densidades de 83g L-1 (D1), 125g L-1 (D2), 168g L-1 (D3) e 206g L-1 (D4). Os peixes foram amostrados antes do transporte (AT), logo após o transporte (chegada) (DT) e 24h depois. A qualidade da água foi monitorada antes da captura dos peixes nos tanques de depuração, após o transporte nos sacos plásticos e nos tanques de recuperação. O oxigênio da água diminuiu para valores inferiores a 4mg L-1 em D2, D3 e D4, a temperatura esteve em torno de 32&deg;C, pH 6,5-6,78, a amônia total foi de 1,09-1,7mg L-1, a amônia não-ionizada foi de 3,58-9,33 x 10³mg L-1 e alcalinidade 134-165mg CaCO3 L-1. O cortisol plasmático e a glicose sanguínea aumentaram após o transporte nos peixes em todas as densidades ensaiadas, voltando aos valores controle 24h depois. Os valores de osmolaridade não mudaram logo após o transporte, mas aumentaram 24h depois de modo igual em todas as densidades. O cloreto plasmático diminuiu na chegada, de modo inversamente proporcional à densidade de carga. O hematócrito diminuiu 24h depois da chegada dos peixes, em todas as densidades testadas, mas não houve diferença no número de eritrócitos. Não houve mortalidade até uma semana após o transporte. O matrinxã mostrou ser uma espécie tolerante a altas densidades de carga em embalagens para transporte além de suportar baixos níveis de oxigênio na água