In a 30-day experiment, Farfantepenaeus brasiliensis PL 25 (25 AE 10 mg;17.9 AE 1.6 mm) were raised in nine circular £oating cages with a stocking density of 1000 shrimp m À 3 . Three treatments were evaluated:(1) culture in BFT system plus a commercial feed supply (BFT1CF); (2) culture in BFT system without feed supply (BFT) and (3) culture in clear water with feed supply (control). Post-larvae (PL) ¢nal weight (218.9, 236.5 and 176.0 mg, for BFT1CF, BFT and control respectively), ¢nal biomass (17.9, 15.7 and 8.2 g) and weight gain (193.9, 211.5 and 151.0 mg) were similar in the BFT regardless of whether they were fed a commercial diet (P40.05), but were both signi¢cantly higher than the control (Po0.05). Survival (81.5%, 67.0% and 84.8% respectively) and ¢nal length did not di¡er between treatments (P40.05). The bio£oc analysis identi¢ed ¢ve main microorganism groups: protozoa (ciliate and £agellate), rotifers, cyanobacteria (¢lamentous and unicellular) and pennate diatoms. Free living bacteria and attached bacteria in bulk were 25.73 AE 8.63 and 0.86 AE 3.17 Â 10 6 mL À 1 respectively. Proximate analysis in the bio£oc indicated high levels of crude protein (30.4%). Results con¢rmed favourable nutritional quality of bio£oc, and enhanced growth and production of F. brasiliensis PL in bio£oc systems.

Farfantepenaeus paulensis juveniles (72 ± 24 mg), were reared in a suspended microbial flocs system and fed practical diets containing increasing amounts of crude protein (250, 300, 350, 400 and 450 g kg−1 CP). Development of microbial flocs was promoted by high aeration rates and fertilization with wheat bran and molasses. Flocs were composed of detritus in the form of flocculated matter colonized by heterotrophic bacteria, cocoid and filamentous cyanobacteria, flagellate and ciliate protozoa and rotifers. Proximate composition analysis of the suspended microbial floc showed CP levels of 304 g kg−1. After 45 days, mean shrimp survival were above 89%, with no significant differences between treatments. Shrimp fed diets with 350 g kg−1 or higher CP content achieved significant higher (P < 0.05) final weight (0.66–0.68 g), weight gain (0.58–0.61 g) and instantaneous growth rate (0.049–0.050), with feed conversion rates (2.17–2.30) significantly lower (P < 0.05). Results show that, when rearing is carried out in a suspended microbial flocs system, dietary CP levels can be kept at 350 g kg−1. Furthermore, results confirm that microbial‐based systems allow shrimp culture without compromising the surrounding environment and shows the possible reduction of production costs and fish meal dependence.

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Biofloc rearing media provides a potential food source for shrimp reared in limited or zero water exchange systems. This culture system is environmentally friendly as it is based on limited water use and minimal effluent is released into the surrounding environment. In this study, we evaluated the survival, growth performance and salinity stress tolerance of pink shrimp Farfantepenaeus paulensis postlarvae reared from PL 10 to PL 25 in a biofloc technology limited water exchange system. PL (mean ± SD weight and length of 14 ± 10 mg and 8.10 ± 0.7 mm, respectively) were reared in nine 40-L plastic tanks with a stocking density of 10PL/L. Three culture treatments were applied (1) culture in the presence of bioflocs and commercial feed supply (FLOC ? CF); (2) culture in the presence of biofloc without feed supply (FLOC) and (3) culture in clear water with feed supply (control). Final biomass and survival were significantly higher in FLOC ? CF treatment than the control (P \ 0.05), but did not differ from FLOC. PL reared in the FLOC ? CF treatment achieved a significantly higher final weight, weight gain and length in comparison with the other two treatments (P \ 0.05). No significant difference (P [ 0.05) between treatments was found for salinity tolerance over 24 and 48 h durations. The proximate analysis of floc shown high levels of crude protein (30.4%), but low levels of crude lipids (0.5%). The continuous availability of bioflocs had a significant effect on growth and survival of F. paulensis postlarvae cultured in BFT nursery systems.

The present study describes the ovarian development stages of wild Farfantepenaeus paulensis (Pe¤ rez-Farfante) through the combined observation of histological and visual characteristics. Twenty-¢ve females (61.872.4 g) were captured in 35^40-m deep waters o¡ southern Brazil (271S). The females were grouped according to the size and shape of their ovary and then killed. The colour of the fresh ovary was compared with a chromatic scale catalogue. Analysis of the histological sections of each ovary determined the morphological characteristics, size and frequency of the di¡erent oocyte types. Based on these characteristics, four distinct stages of ovarian maturation are proposed: stage I (immature), characterized by the presence of small basophilic oocytes (52.1719.9 mm) and ovary colour ranging from translucent to creamy; stage II (developing), with yolky oocytes (YOs) (144.2726.1 mm) and a light green colour; stage III (mature), presenting largeYOs but with cortical rods (235.0730.2 mm) and an olivebrown colour; and stage IV (spent), with atretic oocytes and the same ovary colour pattern as stage I. The gonadosomatic index ranged from 1.6 (stage IV) to 13.7% (stage III) and was closely related to the different ovarian maturation stages. The observation of visual features coupled with histological characteristics was found to represent a reliable procedure to evaluate the ovarian maturation of F. paulensis.