Shrimp polyculture is not yet a common practice among farmers; however, this activity represents an important alternative to solving and ⁄ or minimizing some of the problems that shrimp aquaculture has faced in the past two decades (environmental pollution, diseases and decreasing prices). In this context, many benefits have been achieved with some polyculture practices. Several species from diverse trophic levels have the potential to be co-cultured with shrimps. A good knowledge of the species that are candidates for polyculture and an adequately designed culture system are the most important points to consider when co-culturing shrimp with other species. The present paper is a review of the past, present and future of shrimp polyculture with other organisms.
Shrimp postlarvae were reared into different microcosm systems without water exchange; a traditional system based on simple fertilization to improve microalgae concentration (control), an autotrophic system (AS) based on the promotion of biofloc and biofilm by the addition of fertilizer and artificial substrates and a heterotrophic system (HS) based on the promotion of heterotrophic bacteria by the addition of nitrogenous and carbonaceous sources and artificial substrates. Better growth performance and survival were registered in shrimp from the AS and HS compared to the control. Feed conversion ratios were below 0.7 for all treatments, but AS and HS were significantly lower than the control. Regarding digestive performance, no significant differences were observed for trypsin, amylase and lipase activities among AS and control shrimp; however, shrimp from HS showed a higher trypsin and amylase activities, suggesting a higher digestive activity caused by the presence of microbial bioflocs. The presence of biofilm and bioflocs composed by either autotrophic or heterotrophic organisms in combination with formulated feed improved the growth performance and survival of shrimp. Apparently, such combination fits the nutritional requirements of shrimp.
ABSTRACT. The estuarine diatom Thalassiosira weissflogii (Fryxell & Hasle, 1977) has been widely used as live feed in aquaculture. The growth rate and biochemical composition of microalgae are highly influenced by environmental factors such as, light, salinity and nutrient availability. Salinity is difficult to control in some shrimp laboratories specialized in larvae production, because these laboratories depend upon the levels measured in estuaries or coastal lagoons, which are the water sources for larvae culture. The present study evaluated the effect of different salinities (25, 30, 35, 40, 45 and 50 psu), on the growth and chemical composition of T. weisflogii at three culture phases, under laboratory conditions. The highest growth rate and maximum cell density were found at 25 psu. Decrease in size and striking changes in morphology of the cells were observed at the higher salinities and drastic changes occurred at 50 psu. Protein and carbohydrate content were higher at low salinities (25 and 30 psu) during the stationary phase. The lipid production was higher at low salinities, but diminished as the phase changes occurred; in contrast, the lipid content was unaffected by the growth phase at higher salinities (≥35 psu). The higher growth rate and better biochemical composition were obtained at 25 and 30 psu. Keywords: estuarine diatom, microalgae culture, proximate composition.
Efecto de la salinidad en el crecimiento y composición química de la diatomeaThalassiosira weissflogii en tres fases de cultivo RESUMEN. La diatomea estuarina Thalassiosira weissflogii (Fryxell & Hasle, 1977) ha sido utilizada como alimento vivo en acuacultura. La composición bioquímica del alimento vivo afecta la nutrición de los organismos durante su cultivo. La tasa de crecimiento y composición bioquímica de las microalgas están altamente influenciadas por factores ambientales como luz, salinidad y disponibilidad de nutrientes. En algunos laboratorios productores de larvas de camarón, es difícil controlar la salinidad, debido a que éstos dependen de los niveles presentes en estuarios o lagunas costeras, los cuales son la fuente de agua para el cultivo larvario. El presente estudio evaluó el efecto de diferentes salinidades (25, 30, 35, 40, 45 y 50 psu), sobre el crecimiento y la composición proximal de T. weissflogii en tres fases de cultivo, bajo condiciones de laboratorio. Las mayores tasas de crecimiento y la máxima densidad celular se obtuvieron a 25 psu. Se observó una reducción en tamaño y cambios en la morfología de las células a altas salinidades y los cambios drásticos ocurrieron a 50 psu. El contenido de proteínas y de carbohidratos fue más elevado a salinidades bajas (25 y 30 psu), durante la fase estacionaria de crecimiento. La producción de lípidos fue elevada a bajas salinidades y disminuyó a medida que cambiaba de fase; no se observó un efecto de las fases del cultivo sobre el contenido de lípidos en altas salinidades (≥35 psu). La mayor tasa de crecimiento y la mejor composición bioquímica se obtuvieron 25 y 30...
Biofloc culture systems, which are based on the development of microorganisms that recycle inorganic nutrients and organic matter, may contribute to the nutrition of some farmed species. Juvenile red tilapia (Nile Tilapia Oreochromis niloticus × Mozambique Tilapia O. mossambicus) cultured in saltwater were fed pelleted diets in which 0, 33, 67, or 100% of the fish meal was substituted with a vegetable meal mix (corn, wheat, and sorghum meals). The proximate composition of the biofloc produced in the culture systems was evaluated. Four experimental diets and one control diet (isocaloric and isoproteic) were randomly assigned to 15 experimental tanks. Samples of biofloc were periodically collected to measure the total suspended solids, organic matter, and ash content and to determine the protein, lipid, and carbohydrate contents. At the end of the study, variables describing red tilapia production were determined. The biofloc volume, total suspended solids, ash, and organic matter showed significant differences among treatments, but carbohydrate (33.0–39.0%), lipid (2.6–3.5%), and protein (23.7–25.4%) levels were similar. No significant differences were observed in red tilapia survival, final biomass, or feed conversion ratio. We conclude that the substitution of fish meal with vegetable meal in the pelleted feed had no adverse effect on the production response of saltwater‐cultured red tilapia.
The raising demand of fish for human consumption has caused a rise in fish cultivation to become a more intense activity and has increased the need for fish feed formulas for aquaculture. Tilapia are aquatic organisms with moderate protein requirements. One of the traditional ingredients used to develop protein diets is fish meal. Despite its high cost, this supply is of high demand for both aquaculture and terrestrial animals. Efforts to seek for alternative sources of conventional and unconventional proteins are ongoing. The purpose of this study is to review alternative sources of proteins with potential to partially or fully substitute fish meal in tilapia feed. Also, it addresses the challenges that aquaculture feeding is facing regarding the substitution of fish meal with proteins from plant sources.
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