Abstract:
Feed is a major component of production costs in aquaculture, accounting for about 80% of
the production costs. High-quality aquafeeds are a prerequisite to healthy and nutritious fish.
Aquafeeds are expensive owing to the fact that fish oil and fish meals are the main sources of
lipid and protein components, respectively. Having alternative, cheap sources of lipids in the
feeds is therefore important. The brown seaweed (Sargassum portieranum) that is locally
available on the Kenyan coast is known to be rich in omega-3 fatty acids. The objective of this
study was therefore to determine the suitability of brown seaweed dietary supplementation
and its effect on the nutritional quality and growth performance of Nile tilapia (Oreochromis
niloticus).
A total of 180 male Nile tilapia fingerlings were divided into three experimental groups in
triplicate. The fish were assigned to one of the three treatment diets: 0% (control diet), 5%, or
10% inclusion of the brown seaweed, and fed for 12 weeks. The weight and length (from head
to tail) of the fish were measured every two weeks to determine the growth performance. At
the end of the experiment, the fish muscle protein, lipid, and mineral content were
determined using AOAC methods.
Seaweed supplementation significantly (P < 0.05) improved the body weight, length, survival,
and specific growth rate of the fish, with the 10% inclusion showing higher performance than
the 5%. The protein, mineral, and lipid contents of the fish muscles were also significantly
affected by the seaweed supplementation. Fish fed on the 10% diet had the highest total lipid
content in the muscle, at 0.93%, compared to 0.78% in the fish fed on the control diet. The
protein content in the fish muscle was not significantly affected (P < 0.05) by the inclusion of
seaweed in the feed. Overall, the results showed that supplementing the feed with 5% or 10%
brown seaweed improved the growth performance and nutritional quality of tilapia fish. Thus,
including brown seaweed meal in the diet of tilapia fish could offer an effective means to boost
production in aquaculture.
