CANR Study finds optimal weaning age and diet for African bony-tongue fry

A study by the College of Agriculture and Natural Resources (CANR) has identified the optimal weaning age and diet for African bony-tongue (Heterotis niloticus) fry, providing practical recommendations to improve the commercial production of the species.

Led by Dr. Prince Ofori-Darkwa, the study addressed a key challenge in African bony-tongue farming, the limited understanding of the fry's nutritional requirements and the appropriate age to transition them from live feed to formulated diets.

The findings were published in Aquaculture Research.

The researchers evaluated fry weaned at different ages and compared the performance of two formulated diets with varying levels of phospholipids, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA).

A control group was fed live Artemia throughout the experiment.

The study found that early weaning, between 15 and 25 days after hatching, resulted in complete mortality.

However, survival rates increased significantly when weaning was delayed, with the best results recorded among fry transitioned to formulated diets between 65 and 85 days after hatching.

Fry fed the diet enriched with phospholipids, DHA, and EPA consistently outperformed those fed the lower-nutrient diet, achieving higher survival rates, greater weight gain, and improved overall growth.

Although fry fed exclusively on live Artemia recorded the highest survival, the researchers found that introducing a high-quality formulated diet between 65 and 85 days after hatching offers a viable alternative while maintaining strong growth and survival.

Based on the findings, the researchers recommend maintaining African bony-tongue fry on live Artemia during their early development before gradually transitioning them to nutrient-rich formulated diets.

They also call for further research to develop artificial feeds that can replace live prey at an earlier stage, helping to reduce production costs and support the commercial expansion of the species.