#DiscoverWithVSU: Sweetpotato starch improves growth and feed efficiency in tilapia fry

Tilapia farming is one of the cornerstones of aquaculture in the Philippines, but farmers continue to face the challenge of high feed costs, which often account for more than half of total production expenses. 

Commercial feeds rely heavily on protein-rich ingredients like fishmeal, which are not only expensive but also increasingly limited in supply. Because of this, there is a strong need to identify cheaper and locally available alternatives that can support fish growth and survival without compromising quality.

Researchers from the Faculty of Fisheries and Aquatic Sciences (FFAS) from Visayas State University (VSU) Tolosa turned to root crops as possible solutions.

Sweetpotato, cassava, and corn are widely grown in Eastern Visayas, and their starch content makes them potential energy sources in aquafeeds. Carbohydrates like starch provide energy and allow dietary protein to be directed primarily toward growth instead of being burned for metabolism. With this in mind, the researchers investigated whether these root crops could serve as practical feed ingredients for Nile tilapia fry.

The study, conducted by Quenstein D. Lauzon and Mary Ann B. Madeja and published in the Annals of Tropical Research, tested diets containing 15% starch from sweetpotato, cassava, or corn, compared to a control diet made of standard commercial feed. 

Over an eight-week period, 360 tilapia fry were raised under controlled conditions and fed three times daily. The researchers then measured growth performance, feed efficiency, body composition, and survival.

The results showed that sweetpotato starch stood out as the most effective dietary supplement. Tilapia fry fed with sweetpotato starch reached an average final body weight of 3.64 grams, compared to 2.66 grams for the control group, 2.40 grams for those given cassava starch, and 2.83 grams for those given corn starch. These fry also achieved higher weight gain and specific growth rate, meaning they grew faster relative to their size. Their feed conversion ratio, which measures how efficiently feed is turned into body mass, was the lowest among all groups, although not statistically different from the control. 

In terms of nutrition, tilapia fed with sweetpotato starch maintained protein levels comparable to those on commercial feed, while cassava- and corn-fed groups recorded lower protein content. 

Measurements of body length and width confirmed that fish given sweetpotato starch were not only heavier but also larger in size. Importantly, survival rates remained high across all treatments, above 95%, showing that all diets were safe and well-tolerated.

One interesting observation was that the fish accepted all diets equally well. Feed attractability tests revealed no significant differences among the treatments, which suggests that the advantage of sweetpotato starch came from its digestibility and nutritional benefits rather than taste preference. 

Sweetpotato starch is known to gelatinize easily when cooked, making it more digestible for tilapia, which are omnivorous fish with a long digestive tract adapted to handle carbohydrates efficiently. This likely explains the superior growth performance observed in the sweetpotato-fed fry.

The findings of this study have strong implications for fish farming. By incorporating 15% sweetpotato starch into tilapia fry diets, farmers can improve growth and feed efficiency while reducing reliance on costly protein sources like fishmeal. 

At the same time, this approach offers a practical use for locally abundant crops such as sweetpotato, and creates a link between aquaculture and agriculture that can benefit both fish producers and root crop farmers. 

For Eastern Visayas, where these crops are widely produced, the study points to a sustainable way of lowering production costs and making fish farming more profitable.

Beyond contributing to academic knowledge, this research demonstrates how VSU continues to explore practical, science-based solutions for local communities, using the region’s natural resources to address real challenges in food production and aquaculture.

This article is aligned with the Sustainable Development Goal (SDG) 2: Zero Hunger; SDG 8: Decent Work and Economic Growth; SDG 9: Industry, Innovation, and Infrastructure; SDG 12: Responsible Consumption and Production, and; SDG 14: Life Below Water.

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