Preliminary Evaluation on the Potential Utilization of Distiller's Solubles (SLOPS) for the Culture of the Blue Tilapia (Tilapia aurea)

Abstract

Different triplicated treatments of slops, a rum distillation waste product, were compared with treatments of a commercial fish feed, a commercial chicken feed and an inorganic fertilizer to evaluate the potential utilization of the by-product in the cultivation of the cichlid fish Tilapia aurea. (The study was undertaken at the Agricultural Experiment Substation in Lajas and at Magueyes Island, site of the laboratory of the Department of Marine Sciences.) Research began February 8 and ended July 3, 1974 (145 days). Thirty 9.3 m³ plastic pools served as experimental facilities. Fish subjected to the treatments with the raw slops gained weight at a moderate rate, but they also suffered external discoloration and darkening of the body as a result of their direct filtration of the water containing in solution the dark-colored slops. Reproductive activity of the slops-fed fish might have also been affected. The highest production was obtained with the fish feed treatment. This was followed in descending order by the fish in the chicken feed treatment, inorganic fertilizer, yeast extract from slops, other slops preparation, and the control. Water quality indexes such as pH, temperature, dissolved oxygen and turbidity, were monitored throughout the work. The most evident water quality indexes affected were dissolved oxygen and turbidity. Dissolved oxygen levels were reduced dramatically upon initial release of the different slops preparations. The systems recovered after several days in terms of dissolved oxygen levels. Turbidity was very high in the slops treatments. Water in the pools that had not received any of the slops preparation exhibited a greenish color, as an indication of moderate phytoplankton growth. The pH concentration remained within the desirable range (6.5 to 9.0) for fishculture, when measured before daybreak.