Os programas alimentares que adotam estratégias de restrição alimentar com longos períodos de jejum, bem como a superalimentação, podem levar a prejuízos nos sistemas produtivos por não respeitar os aspectos fisiológicos dos peixes. Tendo em conta as características metabólicas de cada espécie alvo é possível elaborar planos alimentares que reduzam de forma expressiva, não somente o consumo de alimento, mas também, o emprego de mão de obra, a taxa de gordura visceral e os custos totais de produção. Ademais, esse tipo de manejo alimentar pode tornar o negócio da piscicultura mais sustentável, uma vez que reduz os níveis de poluição do meio, viabiliza o negócio, reduz a sua sensibilidade às flutuações de preço da ração, bem como, permite ao produtor o melhor uso e gestão da mão de obra. Nesta revisão foram elucidadas algumas características inerentes às dinâmicas fisiológicas e metabólicas de algumas espécies, além dos principais indicadores de sustentabilidade, quando da adoção do manejo alimentar restritivo no cultivo de peixes.Palavras chave: sobrealimentação, ganho compensatório, qualidade da carcaça, mão de obra, planos alimentares ABSTRACT Food programs that adopt food restriction strategies with long periods of fasting, as well as overfeeding, can lead to losses in productive systems by not respecting the physiological aspects of fish. Taking into account the metabolic characteristics of each target species, it is possible to elaborate diet plans that significantly reduce not only food consumption, but also the employment of labor, the visceral fat rate and the total production costs. Furthermore, this type of food management can make the fish farming business more sustainable, since it reduces the levels of pollution in the environment, makes the business feasible, reduces its sensitivity to fluctuations in feed prices, as well as allows the producer the best use and management of labor. In this review, some characteristics inherent to the physiological and metabolic dynamics of some species were elucidated, in addition to the main sustainability indicators, when adopting restrictive food management in the cultivation of fish.

Shrimp color is important when choosing the crustacean by the consumer. Pacific white shrimp Litopenaeus vannamei can convert various types of carotenoids into astaxanthin and accumulate them in its body, giving the desired reddish color. In this study, the shrimps were kept in a biofloc aquaculture system away from the coastal zone, fed with commercial feed supplemented with annatto extract (Bixa sp.). The experiment was carried out with a 2 x 4 factorial design with shad levels (50% and 80%) and four feeding regimes (0, 7, 14, and 21 days) to evaluate the most efficient model to promote the increase in the surface color of the shrimp. Leaching in artificial brackish water and the influence of biofloc pigments on shrimp color. According to the results, bixin sprinkled on the feed surface undergoes leaching in brackish water the measure of the time it is immersed. Carotenoids present in the biofloc showed a correlation with chlorophyll content by the R test. Raceway with 80% water shad and feed containing 1,235 mg/Kg of bixin showed the most significant results in the shell color of shrimps (fresh and cooked) and lower ammonia levels.

Considering that salts are widely used in prawn farming and that studies on their impacts on the aquatic ecosystem have not been identified, this study aimed to evaluate the possible changes caused by acute exposure of Macrobrachium jelskii prawn to sodium chloride and salt marine, through acute toxicity test and histopathological study. Prawn postlarvae (0.2112±0.34 g) were exposed to different concentrations of NaCl, 0 (control) to 26‰; and sea salt, 0 (control) to 35‰; for 96 h. In each duplicate treatment, seven prawns were kept in 2 L beakers for 96 h, with temperature, photoperiod, and pH-controlled, without any loss in the control group. To estimate the median lethal salinity (LS50-96h) the “Trimmed Spearman Karber method” program was used. The LS50-96h for NaCl was estimated to be 14.50‰ with a safety level of 1.45‰ and for the sea salt LS50-96h of 26.35‰ with a safety level of 2.63‰. It was also observed that at the concentration of 23‰ of artificial marine salinity, no mortality was observed, reflecting a narrow line between innocuous and deleterious salinity for M. jelskii post-larvae. At the end of the acute toxicity tests, the prawns were fixed and processed for staining in Hematoxylin and Eosin (H.E), Periodic acid-reactive Schiff (P.A.S), Blue Alcian (A.B), and Immunohistochemistry. For branchial histopathological studies, their histological sections were evaluated with an optical microscope. The main branchial alterations observed were hyperplasia, hypertrophy, cellular swelling, detachment of the respiratory epithelium, pillar cell rupture, some secondary lamella fusions, and necrosis.

The inclusion of natural extracts and solution of synthetic astaxanthin in the Macrobrachium amazonicum diet were tested to verify their effect on performance, body indexes and total accumulation of astaxanthin in the reproductive tissues and gametes of this crustacean in comparison with newly captured wild animals. The experiment was randomized in blocks (five treatments with three replicates). Four groups were submitted, during 20 days, to diets in recirculation tanks: control diet (CONT); diet containing natural extract of “buriti” (CAR); diet with inclusion of natural “urucum” extract (BIXN), diet with synthetic astaxanthin (ASTX) and NATURAL group (not fed with ration). 180 prawns were used, with 60 males (6.08±1.96 g) and 120 females (4.55±1.03 g) distributed in five groups containing four males and eight females each. There were no significant differences in performance and body indexes. The number of released spermatozoids, live spermatozoids, body and egg pigmentation was higher in BIXN and ASTX treatments. The ASTX treatment was superior to the NATURAL group in the body pigmentation of females and eggs and release of spermatophores by males. These results demonstrate that the use of natural and artificial carotenoid pigments in the diet are beneficial for reproduction of M. amazonicum.

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