Anguilla marmorata is one of the species of anguillid eels mainly cultured in the Philippines. As they are known to be predatory, eels are primarily fed with carnivorous diets during their early life stages. Due to this behavior, weaning to an artificially formulated diet during the nursery stage is challenging. As weaning strategies on brackishwater nursery culture of A. marmorata are not highly tackled, this study focused on the development of an effective weaning strategy on the brackishwater nursery culture of A. marmorata elvers. Specifically, this study aimed to evaluate the growth performance of A. marmorata elvers when transitioning from fish meat to fish meal-based formulated feed.
Different weaning strategies on the dietary transition of A. marmorata elver (0.15g) from fish meat (70% fish meat, 23% potato starch, 5% yeast, 2% vitamins and minerals) to fish meal-based (70% fish meal, 23% potato starch, 5% yeast, 2% vitamins and minerals) formulated artificial diet were tested. Treatments include feeding with a combination of fish meat and fish meal (10% and 5% reduction of fish meat per day) and feeding with 100% fish meat and 100% fish meal-based formulated diet throughout the experiment.
After 28 days of culture, results revealed that a gradual reduction of 5% fish meat per day led to a significantly high specific growth rate (SGR), percent weight gain (%WG), and survival (p < 0.05) of A. marmorata elvers. Conversely, the lowest growth performance were observed with elvers fed with 100% fish meal and lowest survival was observed with elvers fed with 100% fish meat. These results indicate that combining fish meat and fish meal as feed ingredients could aid in the effective weaning of elvers to artificially formulated diets. Moreover, a longer weaning period can efficiently facilitate their weaning during the nursery stage.