The culture of the giant Malaysian prawn, Macrobrachium rosenbergii, has been recently introduced in Argentina where some tests are carried out, both by the public and private organization. The culture and rearing of the Macrobrachium rosenbergii consists of two phases: the obtainment of larvae from ovate females, and the development and fattening of these postlarvae until they reach a commercial size. Because the need of brackish water for the first phase, many culturists work only on the second phase, i.e., the final production. The complete cycle, from the ovate female to the final harvest, lasts between 6 and 8 months. The most important elements to be taken into account in the M. rosenbergii culture is water quality, controlling the pH, salitness, temperature, NH3 content, dissolved oxygen and turbidness. The processing depends on the requeriments of the chosen markets. They can be sold complete or only the tails, fresh, frozen or peeled. | El cultivo del camaron gigante de la Malasia, Macrobrachium rosenbergii, ha sido recientemente introducido en la Argentina donde se llevan a cabo experiencias a nivel estatal y privado. El cultivo y la cria de este crustaceo consta de 2 etapas: la obtencion de larvas a partir de madres ovadas, y el desarrollo y engorde de estas postlarvas hasta obtener un tamano comercial. Debido a la necesidad de agua salada para la 1ra etapa, muchas camaroneras se dedican a la realizacion de la 2da etapa solamente, es decir, a la produccion final. El ciclo completo desde la madre ovada hasta la cosecha final dura entre 6 a 8 meses. Dentro de los puntos criticos a controlar en el trabajo de una granja acuatica de cultivo de M. rosenbergii esta el cuidado de la calidad del agua, verificando el pH, la salinidad, temperatura, oxigeno disuelto, contenido de NH3 y turbidez. El procesado del camaron depende de la exigencia de los mercados elegidos. Se pueden vender enteros o solamente las colas, frescos, congelados o pelados.

Background. The crayfish Procambarus acanthophorus has a high potential for cultivation; however, it is necessary to evaluate its performance in polyculture with tilapia as a strategy for sustainable production in the rural sector where resources are limited. Goals. Assess the effect of polyculture of the crayfish and tilapia by measuring survival and growth. Methods. Three methods of cultivation with three replicates were evaluated: T1) crayfish monoculture, T2) polyculture crayfish/tilapia and T3) tilapia monoculture. Nine high-density polyethylene tanks (3 m diameter × 1.2 m deep) were used during the trial. The tilapia were fed commercial feed, 32/5% protein / lipids, while the crayfish were given commercial shrimp feed with 35/7% protein / lipids. The productive efficiency of mono- and biculture was determined based on survival feeding efficiency and growth performance. Results. Contrary to what was expected, interspecific competition, space, food availability, and weight gain of crayfish were similar in all treatments, whereas survival was influenced by the treatment, particularly during polyculture, where it was observed that tilapia affected the survival of crayfish. Unlike crayfish, tilapia maintained similar growth and survival in all treatments. Conclusions. The results indicate that polyculture of crayfish/tilapia in a recirculation system is possible and promotes the use of the water column. However, it is necessary to consider the antagonistic effect between species. | Antecedentes. Los cangrejos de río Procambarus acanthophorus, tiene un alto potencial de cultivo; sin embargo, es necesario evaluar su desempeño en policultivo con tilapia como estrategia de producción sustentable para el sector rural, donde los recursos son limitados. Objetivos. Evaluar el efecto del policultivo del acocil y la tilapia en la supervivencia y el crecimiento. Métodos. Se evaluaron tres esquemas de cultivo con tres réplicas: T1) monocultivo de acocil, T2) policultivo acocil/; T3) monocultivo de tilapia. Nueve tanques de polietileno de alta densidad (3 m diámetro x 1.2 m profundidad) fueron usados durante el estudio. Las tilapias se alimentaron con alimento comercial con 32/5% proteína/lípidos, mientras que a los acociles se les dio alimento comercial de camarón con 35/7% proteína/lípidos. La eficiencia productiva en el mono- y bicultivo se determinó en base a la supervivencia, eficiencia alimenticia y crecimiento. Resultados. Contrario a lo esperado en relación con la competencia interespecífica, espacio y disponibilidad de alimento, fue similar el peso ganado de los acociles en todos los tratamientos, mientras que su supervivencia estuvo influenciada por los tratamientos, particularmente en el policultivo, en donde se observó que la tilapia afectó la supervivencia de los acociles. A diferencia de los acociles, las tilapias presentaron una supervivencia y crecimiento similar en todos los tratamientos. Conclusiones. Los resultados indican que es posible realizar el policultivo de acocil/tilapia en un sistema de recirculación, lo que promueve el aprovechamiento de la columna de agua, considerando sin embargo el efecto antagónico entre especies.

It was studied the distribution patterns of the native European white-clawed crayfish (Austropotamobius pallipes) and the introduced signal crayfish (Pacifastacus leniusculus), and looked at the water chemistry in several streams in the north of the Iberian Peninsula (Cantabrian watershed). Fifty fluvial reaches which were currently or previously inhabited by crayfish and had physical attributes similar to the known habitat requirements of crayfish were sampled. P. leniusculus was the most common species encountered (54 percent of the samples), A. pallipes was found in 19 percent and neither species was recorded in the remaining reaches. In this paper it was determined the relationship between crayfish presence and water chemistry. As neither species inhabits waters with the highest NO2- concentrations found, it seems both species are sensitive to NO2-. Mg+2 and S04-2 concentrations are the factors separating sites with and without crayfish (crayfish inhabit water with higher concentrations of both cations). The main differences between reaches inhabited by native and signal crayfish lies in SO4-2 concentration: higher concentrations favour signal crayfish. Applications to management based on the river water chemistry are proposed

We analyze in juvenile Cherax quadricarinatus fattening stage, the circadian rhythm of total protein levels, activity of proteases, lipases and amylases, and their possible change as a function of morning (8 h) and evening (17 h) feeding. In general, the activity of digestive enzymes of juvenile C. quadricarinatus showed no circadian pattern of secretion of lipases except where there was an increase towards the evening-night and a decrease towards the early hours of the morning. The total protein levels, the activity of proteinases and amylases of juveniles of C. quadricarinatus registered in the midgut gland remained virtually unchanged in all experiments. However, a non-significant tendency to diminish the proteinase activity levels after the feeding pulse was observed, with a return to previous enzymatic levels after 3 h. In contrast, the amylase activity did not show an observable effect by the feeding schedule. The study of the patterns of the digestive enzyme secretion and their possible changes, could be used as a tool to establish the most favorable times of the day for juveniles feeding. | Se analiza en juveniles en etapa de engorde (7 g) de Cherax quadricarinatus, el ritmo circadiano de los niveles de proteínas totales, la actividad de las proteasas, lipasas y amilasas, y su posible modificación en función del momento de alimentación matutino (8 h) y vespertino (17 h). En general, la actividad de las enzimas digestivas de los juveniles de C. quadricarinatus no mostró un patrón circadiano de secreción, a excepción de las lipasas, donde se observó un incremento de actividad hacia la tarde-noche y disminución hacia las primeras horas de la mañana. Los niveles de proteína total, la actividad de proteinasas y amilasas registradas en la glándula digestiva, permanecieron prácticamente inalterados en todos los experimentos. A pesar de ello, se observó tendencia a que los niveles de actividad de proteinasas disminuyan luego del pulso de alimentación, recuperando los niveles anteriores 3 h después, independientemente del horario de alimentación. En cambio la actividad de amilasa no mostró ninguna tendencia por efecto del horario de alimentación. El estudio de los patrones de secreción de las enzimas digestivas y sus posibles modificaciones, podría ser utilizado como una herramienta para establecer los momentos del día más propicios para la alimentación de los juveniles en cultivo.