Animal　food　wastes　arc　a　concern　due　to　the　large　amounts　of　commercial　food　required　for　model　animals　during　the　biological　and　biomedical　research.　Searching　for　sustainable　food　alternatives　with　negligible　physiological　effects　on　animals　is　critical　to　solve　or　reduce　this　challenge.　Microalgae　have　been　demonstrated　to　be　suitable　for　both　human　consumption　and　animal　feed.　In　this　study,　the　possibility　of　using　Chlorella　vulgaris　and　Senedesmus　obliques　as　a　feed　replacement　to　Drosophila　melanogaster,　one　of　the　fly　models　commonly　used　in　biomedical　studies,　was　investigated.　Characteristics　including　the　fly　locomotor　activity,　motor　pattern,　feeding　behavior,　lifespan　and　body　weight　were　assessed.　Results　showed　that　compared　to　control,　the　flies　fed　on　80%　microalga　(80-flies)　in　the　total　weight　(w/w)　had　the　double　increased　apparent　step　size,　while　both　60-flies　and　80-flies　exhibited　longer　travel　distances　(60%:　27.77　+/-　1.99　cm;　80%:　31.50　+/-　3.70　cm)　most　likely　due　to　the　starvation　and　varied　serotonin　levels　in　flies　fed　on　high　percentages　microalgae.　Subsequently,　40-flies　exhibited　less　optimal　growth　performance　with　decreased　body　weights　(0.51　+/-　0.006　mg　vs　0.60　+/-　0.005　mg　for　control)　and　shorter　mean　lifespan　(36　days　vs　55.8　days　for　control.　However,　20-flies　showed　no　statistical　differences　in　all　parameters　tested　with　respect　to　control　flies,　indicating　that　20%　miaoalgae　treatment　did　not　greatly　change　the　primary　food　component　such　as　carbohydrate　which　might　play　a　critical　role　in　fly　performance.　Therefore,　the　inclusion　of　20%　microalgae　could　be　an　alternative　to　fly　standard　food　without　compromising　fly　physiological　performance.　(C)　2019　Elsevier　B.V.　All　rights　reserved.