Abstract Pacu (Piaractus mesopotamicus) is a fish with a high production potential in Brazil. However, one limitation is the excessive amount of ether extract in its carcass, an undesirable characteristic for the consumer. One approach to overcome this limitation is to improve carcass quality through zootechnical additives such as caffeine. The aim of this study was to evaluate the effect of supplementing the diet of pacu with caffeine on cut yield, biological indices, and carcass composition. Two hundred pacu with an initial weight of 1,687 g were used. The animals were allocated to 20 aquaculture cages of 1 m³, with 10 animals per cage. A completely randomized design with four treatments and five replicates was used. The treatments evaluated consisted of four inclusion levels of caffeine: T1 = 0.00 g; T2 = 0.16 g; T3 = 0.32 g, and T4 = 0.48 g caffeine.kg-1 of feed. The findings show that caffeine can be recommended as a diet supplement for carcass improvement of pacu, reducing the fat content and increasing the protein content of the carcass. Caffeine up to 0.32 g.kg-1 of feed can be added to the diet of pacu without affecting its performance or cut yield. Piaractus mesopotamicus Brazil However consumer yield indices composition 1687 687 1,68 used 2 m³ m cage T 000 0 00 0.0 016 16 0.1 032 32 0.3 048 48 0.4 caffeine.kg1 caffeinekg1 caffeinekg caffeine.kg kg caffeine.kg- g.kg1 gkg1 gkg g.kg g.kg- 168 68 1,6 0. 01 03 3 04 4 kg1 6 1,

Resumo: Estudou-se o tecido germinativo ovariano do peixe Melanotaenia boesemani. Por meio de análises morfológicas das gônadas, realizadas após a confecção de lâminas histológicas elaboradas em parafina e coradas com hematoxilina-eosina, foram descritos os tipos celulares encontrados e realizada a classificação do estádio de maturidade dos peixes. Macroscopicamente, foi identificado que a referida espécie possui ovário único, arredondado e, na fase observada, amarelado, localizado na parte látero-anterior da cavidade celomática. As fêmeas analisadas foram classificadas na escala de desenvolvimento gonadal como maduro/em reprodução. A presença de folículos vazios e marcas de desova nas lamelas ovulígeras mostrou-se evidente. Nos ovócitos vitelogênicos deste peixe, foi constatada a presença de filamentos de adesão ovocitária ancorados à zona pelúcida. Os ovários apresentaram aspecto morfológico geral semelhante ao de outros peixes teleósteos. Seu tipo de desova foi classificado como intermitente e o padrão de desenvolvimento de ovócitos, como assincrônico.

Abstract: The germinal ovarian tissue of the fish Melanotaenia boesemani was studied. By means of morphological analyses of the gonads, performed after the manufacture of histological slides made of paraffin and stained with hematoxylin-eosin, the cell types found were described and the rank of the maturity stage of the fishes was executed. Macroscopically was found that the species has only one ovary, rounded and in the observed phase yellowish, located in the lateral front part of the coelomic cavity. The observed females were classified in the gonadal development scale as mature/in reproduction. The presence of empty follicles and spawning marks on ovigerous lamellae proved to be evident. In vitellogenic oocytes of this fish, the presence of filaments of oocyte adhesion anchored to the pellucida zona was found. The ovaries showed general morphological appearance similar to that of other teleost fishes. Its spawning type was classified as intermittent and the pattern of development of oocytes as asynchronous.

Peixes cultivados mostram-se altamente sensíveis a dietas deficientes em ácido ascórbico com sinais clínicos que afetam o desempenho e a comercialização por provocar deformidades. Com objetivo de conhecer os níveis mínimos para a melanotênia-maçã, foram testadas seis rações isoaminoacídicas e isocalóricas com níveis variados de vitamina C ativa. Ao final dos 42 dias experimentais, 36 peixes foram analisados histologicamente quanto à porcentagem de tecido conjuntivo e fibras musculares a fim de determinar a influência da porcentagem de Vitamina C nesses índices. Apesar de as médias serem estatisticamente iguais do ponto de vista quantitativo, qualitativamente os níveis mais altos de vitamina C possibilitaram melhor estrutura tecidual. A desestruturação do tecido muscular é um indicativo da deficiência alimentar com ácido ascórbico.

Farmed fishes are highly sensitive to diets deficient in ascorbic acid with clinical symptoms that affect performance and commercialization for causing deformities. Aiming to meet the minimum levels for red rainbow fish, six isoaminoacid and isocaloric diets with varying levels of active vitamin C were tested. At the end of 42 days experimental period, 36 fishes were histologically analyzed for the percentage of connective tissue and muscle fibers in order to determine the influence of the Vitamin C percentage in those ratios. Although the averages are statistically indistinguishable from the quantitative point of view, qualitatively higher levels of vitamin C allow better tissue structure. The breakdown of muscle tissue is indicative for dietary deficiency of ascorbic acid.