Replacement of fish oil with canola vegetable oil-based diets on growth and survival rate of Caspian trout, Salmo caspius fry

Abstract

This study was conducted to evaluate the effects of different levels of canola oil on growth performance and survival rate of Caspian trout (Salmo caspius) fry during replacement with canola oil over a period of 60 days. 180 pieces of fish fry (4.6 ± 0.23 g in weight) with a density of 15 individuals were placed in 300-liter fiberglass tanks. Four treatments each with 3 replicates were fed with diets including 100% fish oil (T1), 100% canola oil (T2), 50% fish oil and 50% canola oil (T3), 70% fish oil and 30% canola oil (T4) with the same protein and fat levels of 43% and 14%, respectively. The results showed that the highest weight (26.46 g), final length (13.46 cm) and specific growth rate (2.97%/day) belonged to T3 exhibiting a significant difference with other treatments (p≤0.05). Moreover, the lowest value of feed conversion ratio (1.41) and the highest amount of condition factor (1.17 ± 0.08) were also found in T3. However, these differences were not statistically significant (p>0.05). The highest protein efficiency coefficient of 2.37 was found in T4, exhibiting a significant difference with other treatments (p≤0.05). The survival rate among all treatments was 100% (with no mortality). Based on the results, it can be concluded that the partialy replacement of fish oil with canola oil (50% fish oil with 50% canola oil) in the diet of Caspian trout not only has no negative impact on growth indices and survival rate, but also can enhance these indices and decrease costs by reducing the length of the culture period.

Keywords

• caspian salmon
• salmo trutta caspius
• canola oil
• fish oil
• growth performance
• survival