B. splendens, a worldwide widespread species (Alderton & Guibbs, 2011), belongs to the anabantid family and has a carnivorous feeding habit, a wide variety of colours, sizes, openings and shapes of the tail fin, in addition to the ability to capture atmospheric oxygen and little demand for management, outstanding characteristics of the species.In all its breeding stages, quality food is of fundamental importance for the proper development of Bettas (Faria et al., 2006). However, adequate feed formulations are essential for the good development of a species (Furuya, 2010; NRC, 2011). In fish diets, the main protein source of animal origin used is fishmeal, however, due to the high demand and environmental consequences of this ingredient, a reduction in its supply is expected (Silva et al., 2017).Thus, the aquaculture food industry seeks to adapt by investigating alternative protein sources with high availability in the market and attractive palatability that can be included in diets for fish, thus reducing food waste (Apper et al., 2016;Tantikitti, 2014).Currently, factors such as availability, good biological quality and low cost of agro-industrial co-products arouse interest in their use in animal

The objective of this study was to evaluate the inclusion of increasing levels of a commercial mix of essential oils (EOs) from cashew (Anacardium occidentale) and castor bean (Ricinus communis) as an additive in diets for Nile tilapia. Thus, 240 juveniles with an initial weight of 35.06 ± 1.02 g were distributed in a completely randomized design (four treatments and six replicates) in 24 cylindrical‐tapered tanks; the fish were fed for 60 days, four times a day, diets containing increasing levels of EO (0.10, 0.15 and 0.20%) and a control diet (without the additive). After the experimental period, the animals were desensitized, and an aliquot of blood was collected for the biochemical analysis; they were subsequently euthanized for the evaluation of productive performance and fillet chemical composition. No significant differences (p > .05) were observed in the analyses of productive performance, fillet chemical composition, and triglycerides, VLDL, total proteins, urea and glucose. However, significant differences (p < .05) were observed in the analyses of total cholesterol, HDL and LDL. Inclusion above 0.15 of the additive showed an improvement in the levels of lipoprotein carriers, increasing HDL levels and decreasing LDL values, without interfering with the fish productive performance.

The objective of this work was to determine the effect of L-carnitine supplementation on the productive performance and physiology of juvenile pacu (Piaractus mesopotamicus). A total of 288 pacu, with an initial average weight of 9.62±0.74 g, were fed experimental diets supplemented with 400, 800, 1,200, 1,600, and 2,000 mg kg-1 L-carnitine and a control diet (without supplementation), for 128 days. The following were evaluated: growth performance; carcass centesimal composition; intestinal, muscle, and hepatic histomorphologies; and oxidative stress. The fish hepatosomatic and viscerosomatic fat indexes increased with the inclusion of L-carnitine in the diets. The evaluation of carcass centesimal composition showed that the diets supplemented with 2,000 mg kg-1 L-carnitine caused a reduction in protein content and an increase in that of ethereal extract. Intestinal histomorphology indicated changes in the villi with L-carnitine supplementation. Moreover, hepatic lipid peroxidation occurred with the inclusion of 2,000 mg kg-1 L-carnitine. The supplementation with L-carnitine in the diets of pacu juveniles does not influence the development of the fish until the rate of 1,600 mg kg-1. However, high carcass lipid levels, as well as an increase in the hepatosomatic and viscerosomatic fat indexes, are observed in fish fed diets containing 2,000 mg kg-1.

The purpose of this study was to evaluate different lipid sources in diets for silver catfish juveniles regarding aspects of productive performance, centesimal composition, hepatic histology, biochemical responses, and oxidative stress. A total of 300 juveniles with an initial mean weight of 18.45 ± 1.22g were distributed in 20 net-pens of 1m3, arranged in a 200 m2 masonry tank, for a period of 90 days. The experimental diets were isoprotein (29.05% digestible protein) and isoenergetic (3,250 kcal.kg-1), containing different sources of oils (soybean, sunflower, fish, canola and olive) at a concentration of 3.0%. The animals were distributed in a completely randomized design, with five treatments and four replicates. The data were submitted to ANOVA, and the means, when significant, were compared by the Tukey test at 5% significance level. Visceral fat index was higher for fish fed diets containing sunflower oil (P<0.05). No differences (P>0.05) were observed for the variables of productive performance, centesimal composition, and blood biochemistry. A difference (P<0.05) was observed in hepatic histology, where the treatment with soybean oil had a higher number of hepatocytes. The animals fed with fish oil had a higher TBARS lipid peroxidation and a higher GST enzyme activity (P<0.05). Therefore, the different lipid sources can be used to feed this species without any damage to productive performance. It is not advisable to include sunflower oil, as it provides greater deposition of visceral fat.

This study is aimed at assessing the feeding frequency for tilapia fingerlings. 240 fishes were randomly distributed in 24 containers. The feeding consisted of six frequencies: 4 (F4), 5 (F5), 6 (F6), 7 (F7), 8 (F8), and 9 (F9) times a day. The weight gain was significantly higher in F5 and F6 when compared to F4 ( p = 0.0409 and 0.0306, respectively). Feed intake and apparent feed conversion did not differ between treatments ( p = 0.129 and p = 0.451 ). About water quality, the nitrogen levels in the water from the treatments differed between F4 and F5 ( p = 0.0478 ) and F4 and F6 ( p = 0.0283 ) and for P between F4 and F6 ( p = 0.0215 ) and F4 and F9 ( p = 0.0432 ). The x 2 test showed a dependence relationship between feed frequencies and the muscle fibers frequency ( p < 22 × 10 − 17 ), prevailing fibers between 10-20 micrometers in F4, F5, F6, and F7 and 30-40 in F8 and F9. The area of the hepatocytes differed only between F5 and F9, while the nucleus area did not. Partial net revenue differed in 10% between F5 and F4 ( p = 0.0812 ) and between F6 and F4 ( p = 0.0568 ). In conclusion, fingerlings fed 5 to 6 times a day have better zootechnical and partial recipes.

This study evaluated the effects of a probiotic additive on reproductive variables of the silver catfish (Rhamdia quelen). Three hundred juveniles (initial mean weight 17.35 ± 0.97 g) were fed for 90 days with diets containing increasing levels of a probiotic additive (0.15, 0.30, 0.45 and 0.60 g/kg of feed), which consisted of a blend between Bacillus subtilis and B. cereus, both at a concentration of 4 × 1011 CFU/g, and a control diet without the additive. In males, the presence of the probiotic had an effect on relative seminal volume, sperm cells’ survival, gonadosomatic, hepatosomatic and viscerosomatic indexes, as well as transpose beat frequency, displacement velocity, motility rate and straightness of sperm cells. In females, the probiotic inclusion resulted in presented better in spawning and fertilization rates, viscerosomatic fat accumulation and development of germ cells. Additionally, the hepatic integrity and hepatocyte developmental characteristics were preserved by the presence of the probiotic additive. Thus, the inclusion of 0.60 g/kg of the probiotic could be recommended for the improvement of the reproductive performance of R. quelen.

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It is widely accepted that broodstock nutrition or enriched diets with certain compounds greatly impacts fish reproductive performance, especially the input of different concentrations of fatty acids (especially polyunsaturated ones). Thus, here we evaluated  reproductive variables in male catfish (Rhamdia quelen) of 18.45 ± 1.22 g fed with diets containing different lipid sources: fish, canola, sunflower, soybean and olive oils. 300 juvenile R. quelen were randomly distributed in 20 net-tanks (1m3) disposed inside a 200 m2 masonry pond, and the experiment was composing five treatments with four replicates, and were fed during 90 days, with a 3% inclusion level of the oils in the diets. The histological evaluations of the fish testicles were characterized in the final development stage and maturation in all animals, regardless of the offered diet. Spermatic normality, seminal volume, total sperm production, seminal pH and testosterone level did not present significant differences among treatments. Higher sperm concentration was more pronounced in males fed a diet containing sunflower oil. Parameters obtained by computer-assisted sperm analysis (CASA) showed that the poor sperm quality were verify when fish were fed diets containing olive and canola oil. The gonadosomatic, hepatosomatic and viscerosomatic fat indexes of the animals were similar, regardless of the supplied lipid source. In a practical perspective, we concluded that soybean and sunflower oils can be used as replacement to fish oil in diets for male specimens of R. quelen while the canola and olive oils should be avoid, because decrease the sperm quality.