کیانوش کلانتر نیستانکی

Feed preparation is the main part of the current expenditure of intensive aquaculture production. Insects might be used as whole and alive or as dried larvae to feed ornamental aquatic animals. Insects are usually produced using food waste and locally available materials. Also, they can be used as sources of oil, protein and other valuable compounds including chitin in aquafeed. Industrially produced insects have characteristics such as a short life cycle, low feed conversion ratio, the possibility of breeding on a large scale and high density with low-value feed sources. The amino acids profile of insects is suitable for feeding aquatic animals; they also have sufficient protein contents. Among the insects, the black soldier fly, mealworm and house fly are common. However, the black soldier fly is the most suitable terrestrial insect species for feeding ornamental fish, because its growth period is shorter compared to other species, and it does not also transmit diseases due to the lack of nutrition when it matures.

The present study was carried out to investigate the effect of replacing soybean meal with canola fermented by Bacillus sp. isolated from Caspian Sea sediments on the liver and intestine tissues of Nile tilapia fingerlings. A total of 225 spicemns with an average weight of 1.9±0.05 g were fed five different experimnetal diets including, treatment 1, diet without fermented canola, treatment 2, diet containing 12.5%​ fermented canola, treatment 3, diet containing 25% fermented canola, treatment 4, diet containing 37.5% fermented canola and treatment 5, diet containing 50% fermented canola, for 8 weeks. The results revealed that there were no statistically significant differences regarding pathological changes in the liver tissue such as hepatocyte degeneration, liver fatty change, inflammation, disorganized hepatocytes and haemorrhage among different experimnetal groups (P>0.05). Intestinal tissue examination also showed that no significant differences were observed regarding inflammation and tissue necrosis scores (P>0.05). In conclusion, it was possible to completely replace soybean meal by fermented canola meal in Nile tilapia fingerlings diet to the extent that the product constituted 50% of the finished feed.