The effects of linoleic to linolenic fatty acids ratios on growth performance, feed conversion ratio, visceral and hepatosomatic indices of three spot gourami (Trichopodus trichopterus) brooders

In this study, the effects of different inclusion levels of two fatty acids (linoleic/linolenic fatty acids; LA/LNA) including the ratios of control, 0.5, 1, 2, 4, and 8 were examined on growth performance, feed conversion ratio, and visceral and hepatosomatic indices in three spot gourami (Trichopodus trichopterus) over a 90-day culture period. The results showed that with increasing the LA/LNA ratio in the diet, no significant effects were observed on the condition factor and the average daily growth rate (p>0.05). The final body weight, total and fork lengths showed an increasing trend with increasing LA/LNA ratio (p<0.05); so that, the highest values were recorded in the ratio of 8 despite the lack of significant differences between the levels of 0.5 to 4. The highest percentages of weight and length increments were obtained in the ratio of 8, which showed a significant difference with other treatments (p<0.05); however, there were no significant differences in specific growth rate in body length and weight gains between treatments (p>0.05). The values of both visceral and hepatosomatic indices increased from the control group to a ratio of 2, but a significant decreasing trend was observed at levels with a ratio of 4 and 8 (p<0.05). The feed conversion ratio showed significantly better values in ratios 4 and 8 compared to other ratios (p<0.05). The monthly trend of specific weight growth rate in different treatments showed that treatments with ratios of 4 and 8 showed the higher growth rate in the third month compared to the second and first months of culture period. Based on the results and in order to produce farmed brooders, it can be suggested that the inclusion of 4 and 8 ratios of LA/LNA (in diets without fish oil) resulted in higher growth and nutritional performances in three-spot gourami fish.