Microalgae Ankistrodesmus gracilis as feed ingredient for ornamental fish Xiphophorus maculatus

Abstract

A trial evaluated the effectiveness of macrophytes, <em>Azolla caroliniana</em> (AAC) and <em>Lemna minor</em> (ALM) as a culture media for microalgae <em>Ankistrodesmus gracilis</em>, and their possible use as feed ingredient for ornamental fish. Water quality in all aquariums was adequate for the growth of <em>Xiphophorus maculatus</em>, whilst pH acidity in inert diet (ID) treatment and high content of P in AAC diet treatment did not interfere in fish development. Growth performance parameters were higher (<em>P</em> < 0.05) in ALM diet treatment, except condition factor and feed conversion ratio, with similar rates (<em>P</em> > 0.05) in all diet treatments. Survival was above 75% and total length was similar (<em>P</em> > 0.05) for ID and AAC diet treatments. Lipid levels ranged between 7 and 11%, and was enough to maintain high survival rates (> 80%) and weight gain above 0.42 g to mixed diet (AAC and ALM) and 0.27 g to inert diet. <em>Ankistrodesmus gracilis</em> and macrophytes as a culture media are useful as functional ingredients, because biomass may be incorporated with the food supplement for <em>X. maculatus</em> to enhance nutrition quality and to maintain high growth performance. Although <em>A. caroliniana</em> and <em>L. minor</em> may be used with culture media, <em>L. minor</em> provided the best results to microalgae growth biomass and ornamental fish.