Resumen de Effect of spirulina (Arthrospira platensis) supplementation on tilapia (Oreochromis niloticus) growth and stress responsiveness under hypoxia
Ignacio Plaza, José L. Garcia, Morris Villarroel Robinson
Several recent studies have shown that Arthrospira sp. supplementation of feeds has a beneficial effect on fish health and growth, but less is known about its possible effects on stress responsiveness. The present study was designed to evaluate using Arthrospira platensis as a feed supplement for Oreochromis niloticus fry, reared in recirculating aquaculture systems. Two isocaloric and isonitrogenous fishmeal-based diets were prepared with 0% and 1% A. platensis and fed to fry, approximately 10 mg live weight at the beginning of the experimental period (n=16 tanks, 8 tanks per treatment), at a feeding rate of 6% live weight, four meals a day for 50 d. The weight gain per tank, specific growth rate and feed conversion ratio were similar among treatments but A. platensis supplementation significantly increased survival (p<0.05). Stress responsiveness was measured in all fish from 12 tanks using a non-invasive two-choice test. All fish from one home tank (n=6 tanks per treatment), were placed into a shaded tank where oxygen levels were slowly reduced. A doorway was then opened to a second illuminated tank with normal oxygen levels and the number of fish that left the home tank were counted. The fish fed A. platensis stayed significantly (p=0.001) longer in the home tank (30.20 min ± 13.22) than controls (17.35 min ± 8.32), suggesting a lower stress responsiveness and a higher tolerance to hypoxia.
