The prophylactic use of potassium permanganate (KMnO4) and oxytetracycline and its effects on catfish growth were assessed. For eleven weeks, healthy channel catfish, Ictalurus punctatus, juveniles were exposed to KMnO4 and oxytetracycline. KMnO4‐treated fish were exposed to 1 ppm twice a week for 1 h, while oxytetracycline‐treated fish received a 50 mg/kg dose in the feed (35 fish per tank, two tanks per treatment). Assessed parameters included body weight and length, specific growth rate (SGR), feed intake (FI), condition, and feed conversion index (FCI). Potassium permanganate did not have a suppressive effect on growth, while oxytetracycline significantly enhanced growth on channel catfish (weight and length), as they were heavier (12.5%) than KMnO4‐treated fish and controls at the end of the trial. SGR (%/d), FI, and FCI were not significantly different (P > 0.05) among the three groups of fish. Condition index (K) was significantly higher (ANOVA, P < 0.05) in the oxytetracycline‐treated fish. The present study suggests that, at concentrations commonly used in aquaculture, exposure of healthy channel catfish to oxytetracycline enhanced growth, while KMnO4 does not induce growth suppression.

No abstract

The spatial distribution of Farfantepenaeus shrimp was analysed in the Laguna Madre of Tamaulipas, Mexico. Sampling was carried out on submerged aquatic vegetation (SAV) habitats at five sites located along the coastal lagoon. Two nocturnal surveys were conducted during winter in 2005 (January–February), collecting a total of 3268 shrimp individuals. SAV beds were composed of a mixture of drift algae (mainly Digenia simplex), attached algae (mainly Penicillus capitatus and Udotea occidentalis) and seagrass (mainly Halodule wrightii). Farfantepenaeus aztecus was more abundant (39.5%) than F. duorarum (36.8%), and the remaining 23.7% corresponding to small unidentified Farfantepenaeus spp. were classified as recruits. Abundance of F. aztecus was significantly higher at sites 2 and 4, whereas F. duorarum did not show significant distribution differences along the Laguna Madre. Recruits, juveniles and total shrimp tended to decrease significantly at the northern part of the lagoon (site 1), where substrate was dominated by drifting algae and seagrasses were scarce or absent. The abundance of shrimp was positively related to seagrass biomass and/or water temperature, whereas there was a negligible or negative relationship with algal biomass. With the exception of subadults, a significant positive linear relationship between seagrass and shrimp abundance was fitted, indicating an increase in number of individuals of both species with increasing seagrass biomass. This suggests that seagrass is the most important component of SAV beds influencing the abundance of F. aztecus and F. duorarum along this hypersaline coastal lagoon.

Studies in cage‐cultured fish have reported spatial and temporal variations on parasite prevalence; however, most of these studies have been carried out in cold water and marine environments. Channel catfish, Ictalurus punctatus, is the main floating cages‐raised species used in intensive fish culture in Tamaulipas. In Mexico, there are no seasonal reports on fish parasites in this type of cage system. The aim of the present study was to determine the prevalence and mean intensity of ectoparasites of cage‐cultured channel catfish in a year. Fish were sampled bimonthly from six locations in Tamaulipas and measured and evaluated for ectoparasites. Results showed the presence of two gill‐dwelling metazoans, Ligictaluridus floridanus and Ergasilus cerastes and one skin‐dwelling protozoan, Trichodina sp.; a pattern characterized by peaks in prevalence in early autumn for L. floridanus and late autumn for E. cerastes was observed. In addition, geographic location had a significant effect on the prevalence of L. floridanus and E. cerastes. It was also observed that presence of these parasites was not associated with any fish mortality. To our knowledge, this is the first seasonal study on ectoparasite prevalence on channel catfish reared in cages in México.

RESUMENObjetivo. Evaluar los efectos del estrés agudo debido al manejo y captura sobre los parámetros hematológicos y bioquímicos en bagre de canal (Ictalurus punctatus) bajo cultivo. Materiales y métodos. Los peces (200 g promedio) fueron mantenidos en tanques de cultivo y divididos en dos tratamientos, por duplicado, (n= 15 x 2 x 2 = 60 peces). Treinta bagres fueron expuestos por 5 min a estrés agudo (TE) por manejo y captura, mientras que otro grupo no (grupo control, TnE). Diez peces de cada tratamiento fueron colectados a las 0, 6, y 24 h post-estrés para la extracción de sangre, los bagres del TnE fueron anestesiados durante su manejo y captura. Se evaluó el hemograma (método manual) y bioquímica sanguínea (espectrofotometría). Los resultados fueron analizados mediante la prueba de t student. Resultados. El contenido de eritrocitos, hematocrito, hemoglobina y glucosa de los animales TE fue significativamente mayor (p<0.05) a las 6 h post-estrés en comparación de TnE. Las células inmune en peces TE disminuyeron a las 6 y 24 h post-estrés, siendo leucocitos y linfocitos significativamente menores en el TnE (p<0.05) a las 24 h post-estrés. Otros parámetros evaluados no presentaron diferencias significativas en lo largo del estudio. Conclusiones. Los resultados sugieren que varios indicadores hematológicos y bioquímica sanguínea en los peces son alterados por el estrés agudo ocasionado por manejo y captura.Palabras clave: Bagre, bioquímica sanguínea, estrés, valores hematológicos (Fuente:CAB). ABSTRACTObjetive. Evaluation of hematological and biochemical parameters of culture channel catfish (Ictalurus punctatus) under acute stress by management and capture practice. Materials and methods. Fish (200 g mean) were maintained in culture tanks and divided in two treatments, in duplicate, (n=15x2x2=60 fishes). Thirty catfish were exposed for 5 min to acute stress (TE) by management and capture practice, while other group not (control group, TnE). 10 fish for treatment were collected at 0, 6, and 24 h post-stress for blood collection, where TnE fishes were anesthetized along work. Complete blood count (manual method) and blood biochemical (spectrophotometry) of fish samples were evaluated and their results were analyzed using a Student's t-distribution. Results. The 5346 REVISTA MVZ CÓRDOBA • Volumen 21(2) Mayo -Agosto 2016 erythrocytes, hematocrit, hemoglobin and glucose level of TE animals was significantly higher (p<0.05) at 6 h post-stress, in comparison of TnE. Immune cells in fish TE decreased at 6 and 24 h post-stress, where leukocytes and lymphocytes were significantly lower that TnE (p < 0.05) at 24 h post-stress. Other evaluated parameters did not show significant differences along this study. Conclusions. Those results suggest that several hematological and blood biochemical parameters in fish changed by acute stress generated by management and capture practice.