<b>Association between periphyton and bioflocs systems in intensive culture of juvenile Nile tilapia

Abstract

ABSTRACT. The present work aimed at determining the effects of the association between the periphyton-based system with the bioflocs-based system in the intensive culture of juvenile Nile tilapia (1.56 ± 0.07 g; 72 fish m -3 ), on variables of water quality, growth performance and effluent quality after 10 weeks. The experiment was arranged in a 2 x 2 factorial randomized block design with four treatments and five repetitions each. The factors tested were the following: 'underwater structure' (absence and presence) and 'adjustment of the C: N ratio of water' (no and yes). The final fish body weight, specific growth rate and yield were higher (p < 0.05) in the C: N-adjusted tanks. The presence of submerged structures in the tanks had no significant influence on those same variables. It was concluded that the periphyton-based system is not indicated for intensive farming of Nile tilapia, in which there is a high allowance of artificial feed to fish.Keywords: aquaculture, Oreochromis, limnoculture, limnology.Integração dos sistemas perifíton e bioflocos no cultivo intensivo de juvenis de tilápia do Nilo RESUMO. O presente trabalho teve por objetivo determinar os efeitos da integração do sistema baseado em substrato (perifíton) com o sistema baseado no ajuste da relação C: N da água (bioflocos), no cultivo intensivo de juvenis de tilápia do Nilo (1,56 ± 0,07 g; 72 peixes m -3 ), sobre variáveis de qualidade de água, desempenho zootécnico e qualidade de efluentes, após 10 semanas. O delineamento experimental utilizado foi em blocos ao acaso, em arranjo fatorial 2 x 2, com quatro tratamentos e cinco repetições cada. Os fatores em teste foram os seguintes 'estruturas submersas' (ausência e presença) e 'ajuste da relação C: N da água' (não e sim). Os resultados de peso corporal final, taxa de crescimento específico e produtividade de peixe foram maiores (p < 0,05) nos tanques nos quais se fez o ajuste da relação C: N da água, quando comparado aos tanques sem esse ajuste. A presença das estruturas submersas nos tanques não afetou de modo significativo essas mesmas variáveis. Concluiu-se que o sistema de cultivo de peixe baseado em substrato (perifíton) não é indicado para cultivos intensivos de juvenis de tilápia do Nilo, nos quais há grande entrada de alimento artificial nos tanques de cultivo.

Larvae and fry culture of white cachama ( Piaractus orinoquensis ) in biofloc systems at different carbon/nitrogen (C/N) ratios

“…On the other hand, Pérez‐Fuentes et al (2016) recommend tilapia culture in lower C/N ratios, tending to a C/N ratio of 15/1, similar to that reported by Wang et al (2015) for the cultivation of Carassius auratus , this being an efficient ratio to reduce the concentration of ammonia nitrogen to nitrite and nitrate through nitrification in the culture of aquatic organisms with biofloc (Azhar et al, 2016; Cavalcante et al, 2016; Ekasari et al, 2014; Harini et al, 2016; Khanjani et al, 2016; Syamala et al, 2017; Wei et al, 2016). However, Zapata et al (2017) reported a better growth performance in the rearing of tilapia juvenile ( Oreochromis niloticus ) at a C/N ratio of 10/1, reducing production costs by decreasing the input of organic carbon and oxygen consumption (Xu et al, 2016), being this ratio the one reported by different authors in the culture of species in biofloc system (Crab et al, 2010; Green & McEntire, 2017; Kumar et al, 2015; Suita et al, 2015).…”

“…On the other hand, Pérez-Fuentes et al ( 2016) recommend tilapia culture in lower C/N ratios, tending to a C/N ratio of 15/1, similar to that reported by Wang et al (2015) for the cultivation of Carassius auratus, this being an efficient ratio to reduce the concentration of ammonia nitrogen to nitrite and nitrate through nitrification in the culture of aquatic organisms with biofloc (Azhar et al, 2016;Cavalcante et al, 2016;Ekasari et al, 2014;Harini et al, 2016;Khanjani et al, 2016;Syamala et al, 2017;Wei et al, 2016).…”

<b>Aquatic microbiota diversity in the culture of Nile tilapia (<i>Oreochromis niloticus</i>) using bioflocs or periphyton: virulence factors and biofilm formation

“…Survival rate of the fish was higher than 80% and their final weight was, in average, 7.79 ± 0.82, 28.14 ± 2.7, 24.35 ± 1.04, 26.04 ± 2.07 for T1, T2, T3 and T4, respectively. For further details on the culture system, variables in water quality and zootechnical performance, refer to Cavalcante, Lima, Rebouças, and Sá (2016). It is noticeable that the presence of bioflocs (T1 and T2) and of periphyton (T4) contributed to a higher final weight in comparison to T3.…”

<b>Underwater structures for periphyton in bioflocs tanks for Nile tilapia submitted to feed restriction

“…Schveitzer et al (2013) have observed better shrimp performance in BFT tanks with substrates for periphyton. However, in a previous work carried out in our laboratory, the underwater structures for periphyton in BFT tanks were not efficient in removing nitrogen compounds from the water or as a feeding supplement to Nile tilapia, Oreochromis niloticus, juveniles (Cavalcante, Lima, Rebouças, & Sá, 2016). In that study, however, regular feed rates were employed and, therefore, a great amount of artificial food was provided to the animals.…”