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Background: The cost of feed in fish farming can exceed 70% of the total costs. Thus, the feed industry have sought to formulate balanced diets including low-cost by-products. Objective: To evaluate sunflower meal as a partial substitute (0, 10, and 20%) for soybean meal, with or without phytase supplementation (1,500 FTU/kg) in isoproteic (27% crude protein (CP)) and isoenergetic diets (3,400 kcal/ED/kg of feed) for silver catfish (Rhamdia quelen) juveniles. Methods: A total of 360 fish (weight: 15.77 ± 0.56 g) were randomly distributed in 24 tanks in a completely randomized design following a factorial scheme (3x2) with 4 replicates. The fish were evaluated on the following variables after 90 days: productive performance, hematological variables, histology of intestinal tissue, bromatological composition of carcass, and composition of bone mineral matter. Results: 20% dietary inclusion of sunflower meal improved weight gain and protein efficiency. No difference was observed in the other treatments and no interactions were observed between the other factors. Conclusion: 20% sunflower meal can be included in the feed of silver catfish as a substitute for soybean meal. Phytase inclusion (1,500 FTU/kg) did not improve the nutritional value of the treatments.

Aim of study: To evaluate if dietary restriction influence muscle and intestinal morphology as well as the production performance of juvenile Nile tilapia (Oreochromis niloticus). Area of study: State University of Western Paraná (Universidade Estadual do Oeste do Paraná – Unioeste), Toledo Campus, Brazil. Material and methods: The experimental design was completely randomized with four treatments and five replicates. The treatments were: 7:0 (fed daily; control); 6:1 (fed 6 consecutive days followed by 1 day of fasting); 5:2 (fed 5 consecutive days followed by 2 days of fasting); and 1:1 (fed 1 day followed by 1 day of fasting). A commercial ration with 33.70% crude protein and 4.60% lipid was used, and fish were fed four times daily until apparent satiety for 60 days. Main results: The following parameters were found to have differences among treatments (p0.05) among treatments. The cost of food and partial net revenue were higher in the 7:0 treatment compared to the experimental treatments. Research highlights: Dietary restriction for Nile tilapia in the juvenile phase negatively influences productive performance, centesimal composition, and muscle growth, which demonstrates that this practice is economically unfeasible for commercial production.

Valine belongs to the group of branched-chain amino acids, has an important structural role and is primarily deposited as body protein. The present study evaluated the effects of valine in diets of juvenile Nile tilapia. A total of 216 juveniles with weight of 21.40 ± 0.42 g and length of 10.07 ± 1.00 cm were distributed into 18 aquarium in a completely randomized design with six treatments and three replicates. Six diets containing 24.30% digestible protein, 3,100 kcal/kg digestible energy, and increasing valine levels (0.54; 0.63; 0.72; 0.81; 0.90; 0.99%) were prepared. The following factors were evaluated: performance, chemical composition, blood hematological and biochemical, and skeletal muscle development. Differences were observed in productive performance between treatments for weight gain, daily weight gain and apparent feed conversion, where inclusion levels from 0.81% to 0.99% provide better performances. According to the equation of quadratic regression, the inclusion of 0.86% of valine provided greater weight gain. Regarding the hematological and biochemical parameters, there were differences among the treatments for hemoglobin, triglycerides, and cholesterol. Not difference was observed for the chemical composition and muscle fiber growth. It is recommended the inclusion of 0.86% of valine in the diet of juveniles of Nile tilapia because it provides greater weight gain.

Objectifying to evaluate the inclusion of tilapia processing residues (FT) in the feeding of Nile tilapia (Oreochromis niloticus) fingerlings, 125 Nile tilapia fingerlings (with average initial weight of 0.72±0.19g) were distributed in a completely randomized design with five treatments and five repetitions in 25 aquariums (30L). The rations were formulated to contain 0, 5, 10, 15% of FT and 0% FT plus methionine (0+met). Isoproteics, isocalcitics, isophosphorics and isoenergetics diets were used. After 28 days of experiment, final weight (PF), weight gain (GP), feed conversion ratio (CA) and survival (SO), were evaluated. No differences were observed (P>0.05) for the studied parameters. It was concluded that the FT can be used up to 15% in substitution to the soybean meal in the diet of nile tilapia fingerlings.Objetivando avaliar a inclusão de farinha de resíduos da filetagem de tilápias (FT) na alimentação de alevinos de tilápia do Nilo (Oreochromis niloticus), foram utilizados 125 alevinos de tilápia do Nilo com peso inicial médio de 0,72±0,19g, distribuídos em um delineamento inteiramente casualizado com cinco tratamentos e cinco repetições, em 25 aquários (30L cada). As rações foram formuladas de forma a conterem 0, 5, 10, 15% de FT e 0% de FT mais metionina (0+met), sendo as mesmas isoenergéticas isoprotéicas, isocalcíticas e isofosfóricas. Após 28 dias de experimento foram avaliados as médias de peso final (PF), ganho de peso (GP), conversão alimentar aparente (CA) e sobrevivência (SO). Não foram observadas diferenças (P>0,05) entre os parâmetros avaliados. Conclui-se que a FT pode ser utilizada em até 15% em substituição ao farelo de soja em rações para alevinos de tilápia sem causar prejuízo ao seu desempenho.

The experiment verified the development of Iguaçu´s surubim (Steindachneridion sp.) larvae, submitted to different diets in darkness. 35L-aquariums were used, in a completely randomized design, with five treatments and four repetitions. Each aquarium had 15 larvae with 8,35±0,85 mm and 6,75±0,64 mg, and the treatments were the following diets: Artemia(A); ration(R); zooplankton(Z); Artemia+ration(A+R); and zooplankton+ration (Z+R); After 29 days, the treatments A+R and Z+R was 1036 mg and 859 mg, respectively, significantly higher (P < 0,01), that A and Z, with 536 and 270 mg, respectively. In the treatment R there was no larvae survival, and presented high cannibalism (71%), which was also observed in other treatments, in smaller rates. This results led to the conclusions that the association of live and artificial diets in darkness provided best development, but it does not reduce the cannibalism.O experimento verificou o desenvolvimento de larvas de surubim do Iguaçu (Steindachneridion sp), submetidas a diferentes dietas em ambiente não iluminado. Foram utilizados aquários de 35 litros, em um delineamento inteiramente casualizado, com cinco tratamentos e quatro repetições. Colocaram-se 15 larvas por aquário, com 8,35±0,85 mm e 6,75±0,64 mg. Os tratamentos foram as dietas: Artemia(A); ração(R); zooplâncton(Z); Artemia+ração(A+R); e zooplâncton+ração (Z+R). Após 29 dias, os resultados mostraram que os tratamentos A+R e Z+R obtiveram pesos médios finais de 1036 e 859 mg, significativamente maiores (p < 0,01), que A e Z, com 536 e 270 mg, respectivamente. No tratamento R não houve sobrevivência de larvas, e apresentou alta taxa de canibalismo (71%), o qual foi também observado nos outros tratamentos, em menores taxas. Pode-se concluir que a associação de alimentos vivos e dietas artificiais em ambientes escuros apresenta bom desenvolvimento mas não reduz o canibalismo.

This experiment aimed to control the Ichthyophthirius multifiliis parasite in Steindachneridion sp. fingerlins. One hundred and eighty fingerlins distributed in an experimental delineation entirely randomized, with six treatments and six repetitions in 28L aquariums was used. The treatments had consisted of inoculations and banns: Inoculations with NaCl 1% (T1); Formaline 25 mg.L-1 (T2) and KMnO4 mg.L-1 (T3). For banns, with NaCl 3 % per 10 minutes (T4); Formol 250 mg.L-1 for 1 hour (T5) and KmnO4 mg.L-1 during 10 minutes (T6). The period of the experiment was seven days. The T2 treatment presented better resulted scrumbling 50% the infestation with 80% of survival of the fingerlins registering a significant difference.Este experimento objetivou controlar o parasita Ichthyophthirius multifiliis em alevinos de surubim do Iguaçu Steindachneridion sp. Foram utilizados 180 alevinos distribuídos em um delineamento experimental inteiramente casualizado com seis tratamentos e seis repetições em aquários com 28L. Os tratamentos consistiram em inoculações e banhos: Inoculações com NaCl (T1); Formol 25 mg.L-1 (T2) e KMnO4 2mg.L-1 (T3). Para os banhos, com NaCl 3% por 10 minutos (T4); Formol 250 mg.L-1 por 1 hora (T5) e KMnO4 10 mg.L-1 durante 10 minutos (T6). O período do experimento foi de sete dias. O tratamento T2 apresentou melhor resultado reduzindo-se 50% a infestação com 80% de sobrevivência dos alevinos registrando uma diferença significativa (p < 0,05), em relação aos outros tratamentos. Para alevinos de Steindachneridion sp o formol 25 mg.L-1 inoculados na água por sete dias apresentou melhor resultado no controle de I. multifiliis.