Integrated culture of Nile tilapia and Amazon river prawn in stagnant ponds, using nutrient-rich water and substrates

Abstract

Monoculture is an inefficient aquaculture system because on average <~20% of the diet supplied is assimilated by the target species. Integrated aquaculture systems are attractive alternatives because they take advantage of the wasted nutrients to produce other marketable species. Substrate addition is known as beneficial management to promote natural food (periphyton) by trapping nutrients. Thus, the aim of this study was to evaluate the technical feasibility of integrating the culture of Nile tilapia, Oreochromis niloticus with the culture of Amazon river prawn, Macrobrachium amazonicum in stagnant ponds supplied with water rich in nitrogen and phosphorus, and investigate if the addition of substrates affects the performance of both species. The target species (tilapia) was fed with commercial diet, while the secondary species (prawn) took advantage directly and indirectly of feed wastes. A completely randomized experimental design comprised of three treatments (culture with geotextile blanket substrates, bamboo substrates, and no substrates) with four replicates per treatment was used. Vertical substrates were installed in each pond, which total area was equivalent to 50% pond bottom area. Twelve 0.01-ha earthen ponds were stocked with Nile tilapia (~30 g) and prawn post-larvae (~0.04 g) together, which were cultured for 140 days. Dissolved oxygen, pH and temperature were measured daily, whereas water samples were collected biweekly to evaluate ammonia-N, nitrite-N and nitrate-N. The water quality remained suitable for production throughout the experimental period and was not affected by the use of substrates. The addition of substrates did not affect the growth, survival, productivity and apparent feed conversion ratio of Nile tilapia. On average, Nile tilapia grew to ~0.5 kg, with a survival close to 90%, resulting in productivity of about 5 t/ha. On the other hand, substrates increased the portion of larger prawns in the harvest, improving market value. A major effect was observed using the geotextile blanket substrate. The proportions of prawn heavier than 3 g were 54.2, 41.9 and 25.6% in ponds using geotextile blanket, bamboo and no substrate, respectively. In conclusion, farming Nile tilapia and Amazon river prawn in integrated systems supplied with nutrient-rich water in stagnant ponds is technically feasible. The addition of substrates does not affect tilapia performance but increase the proportion of large prawns; the effect was more pronounced with geotextile substrates.