Gabriele Lara

This research aimed to evaluate the effect of biofloc technology on the intestinal morphometry, productive performance, and survival of juvenile Mugil cephalus. An 87-day investigation was conducted with two treatments, each with three replicates. Treatment one involved rearing juvenile M. cephalus in a biofloc system with a C/N ratio of 15:1, and treatment two involved rearing juvenile M. cephalus with a water exchange and no carbon addition. Ninety (90) juveniles of Mugil cephalus with an average weight of 117.36 ± 6.48 g were randomly distributed into six (6) circular plastic tanks of 250 L (fifteen fish per tank). At the end of the experiment, 10% of each experimental unit’s population was sacrificed for intestinal morphometry analysis. The productive performance was evaluated every 30 days by randomly sampling fish from each tank for biometric measurements, including the specific growth rate (SGR), feed conversion ratio (FCR), condition factor (K), and survival. No structural changes were observed in the intestinal mucosa. The fish reared in biofloc exhibited a similar gut morphometry (villus length and villus thickness) compared to the fish in the water exchange system. The biofloc system does not compromise the gut health of mullet. No significant differences (p > 0.05) were observed in the final weight, weight gain (WG), daily weight gain (DWG), specific growth rate (SGR), condition factor (K), and survival between the treatments evaluated. M. cephalus can be reared using biofloc technology, demonstrating significant water savings compared to water exchange systems.

The addition of organic carbon sources in biofloc technology (BFT) systems promotes microbial community development, enhancing water quality, nutrient recycling, and supplemental feeding through microbial biomass. These characteristics make BFT a viable strategy for the cultivation of promising aquaculture species, such as Mugil cephalus. This study evaluated the effects of three carbon sources—unrefined cane sugar (locally known as chancaca), refined sucrose, and beet molasses—on water quality and growth performance of M. cephalus juveniles reared in a BFT system. Juvenile mullets (4.33 ± 2.09 g) were cultured for 45 days at a stocking density of 0.03 ± 0.01 kg·m⁻³, with biofloc pre-matured in ex situ tanks. Most water quality parameters showed no significant differences among treatments (p > 0.05), except for nitrite concentrations, which were significantly higher in the sucrose group (p < 0.05). The highest growth performance was observed in the sucrose treatment, with a weight gain (WG) of 4.26 ± 0.51 g, an average daily weight gain (AWG) of 0.09 ± 0.01 g, and a thermal growth coefficient (GF3) of 1.27 ± 0.15 at a constant temperature of 24 °C. Bromatological analysis of bioflocs revealed significantly higher crude protein (CP: 9.8%) and energy content (Kcal·100 g⁻¹: 3.44 ± 0.2) in the sucrose treatment compared to chancaca (CP: 5.1%). These findings confirm that M. cephalus can be effectively cultured in BFT systems using simple carbon sources. Refined sucrose, due to its high solubility and nutritional contribution to biofloc formation, is recommended for improving growth performance and system efficiency in M. cephalus production.

Mugil cephalus is an estuarine species that has been shown to acclimate to a diversity of environmental conditions being a good candidate to diversify aquaculture. The objective of this study was to evaluate the growth and water quality of M. cephalus juveniles in a biofloc technology system (BFT). Over a period of 87 days, mullet juveniles (117.36 ± 6.48 g) were reared in two experimental conditions: water exchange (control group) (50% three times a week) and BFT (C:N ratio of 15:1). M. cephalus juveniles were stocked at a density of 7.2 kg·m⁻³. Water quality parameters were monitored periodically. Fish were fed with a balanced artificial feed for marine fish (2% of the total biomass). The water quality parameters were similar between the treatments, with the exception of pH, alkalinity, TSS, and N-NO₃ (p < 0.05). Zootechnical parameters WG, DWG, BG, SGR, condition factor, and survival did not show significant differences (p > 0.05). The biomass gain was higher in BFT (p < 0.05). Water quality variables did not appear to influence mullet survival under culture conditions. Mullet is a species that can be reared in BFT without compromising productive performance and having a significant saving of water.

The potential of polychaetes for the bioremediation of aquaculture sludge gained more attention in recent years. These organisms can reduce organic matter and nutrients contained in the sludge of several aquaculture species, improving the sustainability of these activities. The aim of this study was to evaluate the removal performance of Perinereis gualpensis (Jeldes, 1963) being fed with aquaculture sludge produced by a recirculating system cultivating Atlantic salmon. The experiment involved adding different amounts of sludge (10% and 20% with respect to total substrate) at a density of 300 organisms m⁻² during 30 days. A treatment without sludge served as a control, using natural substrate. The highest removal rate of total organic matter (TOM) (23.95 ± 13.19 g m⁻² day⁻¹) was achieved by P. gualpensis with 20% sludge addition, a reduction of about 36% compared to the total amount added at the beginning of the trials. The organisms fed with aquaculture sludge presented higher nitrogen (8–9%) and carbon (40–43%) contents, with a maximum organic carbon assimilation of 32% in relation to the total content in the sludge. The high survival (88–95%) and positive growth rates (0.28% day⁻¹) achieved by P. gualpensis indicated that this species can be sustained with salmon sludge as the only source of food. These results indicate that P. gualpensis is a promising candidate for removing nutrients from salmon effluents. Moreover, the protein contents achieved by the organisms (52–58%) meet the dietary protein requirements of several aquaculture species. Further research is needed to determine the maximum bioremediation capacity of this species and to evaluate the lipid content and fatty acid profiles of P. gualpensis to determine its potential application in aquaculture feed.

Integrating marine shrimp and tilapia has been shown to be a viable alternative in a system based on bioflocs, but there is no consensus on the spatial arrangement of farmed animals. The present study aims to (1) compare the performance of shrimp and fish in high density when subjected to polyculture (species in the same tank) and multitrophic (species in different tanks) arrangements, and (2) effects on water quality, especially on organic matter (biofloc). The experiment was carried out for 30 days, and three treatments with bioflocs were evaluated in triplicate: control: shrimp monoculture, polyculture: shrimp and tilapia in the same tank, and multitrophic: shrimp and tilapia in separate tanks. The results show that the best product configuration is the multitrophic system, where the biological control of bioflocs took place, and the best performance of the Pacific white shrimp L. vannamei and Nile tilapia O. niloticus was obtained. Tilapia, as an organic consumer, was effective in controlling bioflocs.

A infecção por Mycobacterium spp. tem sido constatada em diversos vertebrados, ocasionando doenças em humanos e animais. As espécies responsáveis pela ocorrência de micobacteriose em peixes, a saber, Mycobacterium marinum, M. fortuitum e M. chelonae, também são potencialmente infecciosas para os camarões peneí­­deos. A micobacteriose que afeta crustáceos corresponde a uma enfermidade sistêmica, granulomatosa, possuindo como agente etiológico bacilos Gram positivos ácido-álcool resistentes. Relata-se neste trabalho a ocorrência de micobacteriose em camarões da espécie Litopenaeus vannamei, sendo identificada a bactéria M. marinum nas amostras teciduais analisadas. Durante a manutenção de juvenis da espécie foram observadas lesões enegrecidas no sexto segmento abdominal de 20 espécimes. A partir das técnicas de Fite-Faraco e Fluorescence In Situ Hybridization (FISH) foi identificado o patógeno, representando uma doença bacteriana com potencial zootécnico que ocorre em ambientes aquáticos, acarretando riscos de contaminação tópica em pessoas envolvidas na manipulação de camarões.

Effects of shrimp confinement in a situation of high density stocking in a long term nursery on their growth performance in grow out ponds. Were analized two nurseries with a density of 2000 shrimp m-2 were stocked at two different times. The first nursery (LTN) lasted 144 days, and the SGR of the animals was 3.0% day-1. The second nursery (STN) lasted 18 days and the specific growth rate (SGR) was 19.9% day-1. On the same day, shrimps were transferred to six lined ponds at a density of 20 shrimp m2 where they remained for 101 days. In the first biometry, the SGR in the LTN treatment, increased to 6.7% day-1 and in the STN it decreased to 5.0% day-1. At the end, shrimps of the LTN and STN treatments reached weights of 8.46 and 6.72 g and had productivities of 1287 and 1015 kg ha-1, respectively. Shrimps reared in nurseries for long periods showed growth and survival rates similar to those obtained using conventional management practices in grow out structures.