Determination of growth performance and feed utilization of fry of goldfish, carassius auratus (Actinopterygii: Cypriniformes: Cyprinidae) fed l-carnitine-supplemented diets

Abstract

Background. A quest continues for alternative feed additives to the content of feeds used in global ornamental fish farming. This study was initiated to see the effect l-carnitine on the growth, feed utilization, and survival rates of goldfish, Carassius auratus (Linnaeus, 1758), one of the most cultivated aquarium fish species in the world. This experiment was carried out since there was no previous study on the effect of the l-carnitine on goldfish. Materials and methods. In this study, five isonitrogenous, isolipidic, and isoenergetic diets (40% protein, 6% lipid, and 14.82 MJ · kg–1 digestible energy, respectively) were formulated. The diets were supplemented with l-carnitine at the dose of 250, 500, 750, and 1000 mg·kg–1 with a non-supplemented diet as control. Goldfish fry was reared in a 65 L glass tank containing aged water. Each dietary treatment was tested in triplicate groups of 20 fish per glass tank. Experimental fish (0.311 ± 0.01 g initial weight) were fed the diets twice daily to apparent satiation for 84 days. In the experiment, diets were evaluated based on growth performance and diets utilization. Results. Supplemental dietary l-carnitine has beneficial effects on improving growth performance, feed conversion ratio, specific growth rate, and protein efficiency ratio in goldfish fry. Conclusion. This study provides first data on the effect of l-carnitine on growth, feed utilization, and survival rates of goldfish. Future research should focus on the growth performance, and feed utilization parameters of other ornamental fish of different conditions of l-carnitine supplemented diets. © 2020, Scientific Society of Szczecin. All rights reserved.