Effect of increasing lipid levels on liver metabolism, intestinal morphology and production performance of discus fish (Symphysodon aequifasciatus)

Abstract

The objective of this study was to evaluate the effects of three levels of lipids in the diet on growth, metabolism, and intestinal and hepatic histopathology in discus fish (Symphysodon aequifasciatus). Fish were stocked in quadruplicate in aquarium (50L) and were fed experimental diets containing three levels (3%, 10%, and 14%) of dietary lipids (LP). At the end of the trial, no significant differences in growth performance were observed. Fish fed diets with 3% and 10% LP exhibited significantly higher protein efficiency rates compared to those fed the 14% LP diet. A significant increase in lipase and alkaline phosphatase activity was observed in fish fed 14% LP diets. The inclusion of 14% lipids in the diet led to a decrease in albumin activity and an increase in the height of the intestinal villi. Although no significant differences were observed in aspartate aminotransferase, alanine aminotransferase activities, and size of hepatocytes. The histopathology of the liver indicated reduced hepatocyte size, lipid vacuoles, and sinusoidal space in the group fed the 3% LP diet. In conclusion, the use of 10% LP diet was found to be more favorable for liver health and growth performance.