This study aimed to evaluate the supplementation of peppermint essential oil (Mentha piperita; PEO) in diets for juvenile Nile tilapia (Oreochromis niloticus). A feeding experiment with diets containing graded levels (0.0, 0.2, 0.4, 0.6, 0.8, and 1.0 g kg⁻¹) of PEO was carried out with fish of 0.58 ± 0.08 g. The inclusion of graded levels of PEO in the diet improved the weight gain (0.52 g kg⁻¹), feed intake (0.51 g kg⁻¹), and feed conversion (0.51 g kg⁻¹) of juvenile Nile tilapia in a quadratic pattern. Increasing levels of PEO also led to a linear decrease in body lipid content. The gut activity of the digestive enzymes amylase (0.54 g kg⁻¹) and protease (0.39 g kg⁻¹) increased quadratically, whereas lipase activity increased linearly. PEO increased the activity of the antioxidant enzymes catalase (CAT; 0.52 g kg⁻¹) and superoxide dismutase (SOD; 0.58 g kg⁻¹) while reducing the production of malonaldehyde (MDA; 0.40 g kg⁻¹) and nitric oxide (NO; 0.63 g kg⁻¹) in the liver. The results of this study provide evidence of the beneficial effects of PEO on the growth and health of Nile tilapia and recommend a dose of 0.6 g kg⁻¹ as the optimal level of supplementation.

The aim of this study is to evaluate the effect of different feeding rates and frequencies on angelfish (Pterophyllum scalare) and severum (Heros severus) larvae. For this purpose, two similar experiments were conducted in parallel. For each experiment, a total of 360 larvae were distributed in 36-1 L aquariums. The experiments were done using a factorial 3x3 completely randomized design, with four replicates. The feeding rates of 50, 100 and 150 artemia nauplii larvae-1 and the feeding frequencies of one, two and four meals day-1 were tested. Parameters of growth performance, uniformity of the batch and survival rate were determined at the end of both experimental periods. No interaction was observed between feed rates and frequencies in angelfish for all parameters evaluated; growth performance was higher in fish fed with 150 nauplii larvae-1, which were divided in two and four meals day-1. The severum larvae presented interaction between feeding rates and feeding frequencies; growth performance was higher in fish fed with two and four meals day-1. Thus, in order to facilitate feed management and reduce manpower costs during ornamental angelfish and severum larvae production, it is recommended to supply 150 artemia nauplii larvae-1 divided in two meals day-1 to fish. Key words: Angelfish, feeding practices, ornamental fish farming, severum.

The aim of this study was to develop pizza dough with different levels of tuna meal (Tunnus spp.). In order to produce tuna meal, tuna torsos without fins were used, cooked for 1 hour, pressed, milled and dehydrated for 24 hours at 60 °C. Pizza dough was produced without (0%) or with the addition of 5, 10, 15 and 20% of tuna meal, calculated based on the quantity of wheat flour. The tuna meal and different pizza pastries were analyzed for moisture content, crude protein, total lipids, ash, carbohydrates, caloric value and fatty acid profiles. Microbiological and sensory analyses were also carried out on the pizza pastries. The increasing addition of tuna meal resulted in gains in the crude protein (10.89 to 18.94%), total lipid (4.63 to 5.89%) and ash (2.54 to 3.54%) contents of the pizza pastries, not influencing the moisture content or caloric value. The inclusion of tuna meal linearly increased the quantity of n-3 series fatty acids in the pizza pastry, from 1.56 to 5.93 g/kg with the addition of 20% tuna meal. The ratio between the polyunsaturated and saturated fatty acids in the tuna meal and pizza pastries varied from 1.21 to 1.85. The microbiological analyses showed that the pizza pastries were produced under proper hygiene conditions. It was also observed that the addition of 5 to 20% of tuna meal to the pizza pastry did not significantly (p>0.05) alter the parameters of aroma, flavor, overall impression and purchase intention. It was therefore concluded that the addition of 5 to 20% tuna meal is effective in improving the nutritional value and fatty acid profile of pizza pastry.