The effect floating and sinking diets on growth performace of juvenile emperor tetra, nematobrycon palmari(eigenmann, 1911).

Efecto en el crecimiento de juveniles Del tetra emperador, Nematobrycon palmri (eigenmann, 1911) con dos dietas: “flotante y hundible”.

The objective of this study was to evaluate the ePect on the growth of juvenile emperor tetra (Nematobrycon palmen) fed a pelleted sinking and floating flake feed. Both were commercially prepared with a protein level of 38%. The experiment was conducted in the laboratory of ornamental fish of the Universidad del Pacifico, eighty fish were selected with an average initial weight of 0.27z0.01 g and 2.3z0.1 cm total length. These were randomly assigned to the two treatments, with 4 replicates each, and density of 10 fish per aquarium. One group was fed the floating flake diet and the second group the pelleted sinking diet. Eight 18-liter plastic tanks were used, each equipped with a sponge filter and aeration system. The experiment lasted eight weeks, the feed was offered twice a day, and water quality parameters were taken periodically. Biometrics were taken and analyses performed to estimate survival, growth, and percent weight gain. The t-student test, with the signifi- cance level p= 0.05, was used to test the hypothesis of significant differences between average values. Fish fed the pelleted sinking feed reached a final weight of 0.61z0.39 g, significantly higher (P<0.05) compared to fish fed the flake diet that had a final weight of only 0.251-0.11 g. Total lengths of fish at the end of the experiment did not diPer (P>0.05) between those fed the pelleted sinking and flake diets, 2.3z0.6 cm and 2.2z0.3 cm, respectively. All fish fed the pelleted sinking diet survived and showed good health througout the study. However, some fish died (7 of 40 fish), without any apparent disease in the group fed the flake diet. Based on this study and other results previously published, a nutrient dense, pelleted sinking (or slow-sinking) feed may be the best alternative for feeding juvenile emperor tetra, and other similar ornamental fish species, in intensive production systems and having a minimal impact on the environmental.