Growth, Survival and Body Protein Content of Swordtail (Xiphophorus helleri) Fed Live and Formulated Feeds

Abstract

Swordtail (Xiphophorus helleri), a commercially important live-bearing ornamental fish, is widely used in aquariums. It is omnivorous in nature and feeds on both live and formulated feeds. There is no study assessing the effect of formulated egg custard, live and commercial feeds on the growth performance and survival of swordtail. Therefore, the study was carried out to investigate the effect of a live feed (Tubifex), formulated egg custard, and two commercial feeds (one aquarium feed and one fish feed) on survival, growth, and body protein content of swordtail in triplicates. Swordtail juveniles (initial weight: 0.46±0.03 g and length: 3.28±0.30 cm) were randomly stocked in glass aquaria feeding ad libitum two times a day. After four weeks of feeding trial, survival of swordtail juveniles was high (≥ 90%) in all treatments and remained unaffected by the dietary treatments (P > 0.05). Differences in growth performance were realized in terms of final weight (g), final length (cm), weight gain (g, %), SGR (%), and metabolic growth rate (g kg-0.8 d-1) (P < 0.05), while swordtail juveniles fed Tubifex and custard showed similar growth performances (P > 0.05). There was a tendency towards a marginally significant difference in daily growth (g d-1, P = 0.077) with the highest growth in juveniles fed Tubifex and custard. Body protein content was remained unaffected by the dietary treatments (P > 0.05) but a trend in increasing body protein content with increasing feed protein was observed. Formulated egg custard used in this study could be a potential feed for swordtail juveniles in terms of availability, cost, ecological and health hazard issues.