Larval mortality is a great challenge to the aquaculture industry. The larval stage has characteristics which make them susceptible to a lot of unfavourable conditions, including (1) Lack of fully functional immune system (2). Lack of fully functional digestive system (3). Compromised osmotic system and host microbe interaction (Faruk & Anka, 2017; Phelps, 2010; Rehman et al., 2017; Vadstein et al., 2013). Research has proved prebiotics as a good source of nutrient to boost immune development across a wide range of fish. This article is focused on the potential benefits of including prebiotics in the diet of larval Nile tilapia (Orechromis niloticus) and the African catfish (Clarias gariepinus).
In the studies of Abdel-Tawwab et al (2008), tilapia fry fed with 1.0-5.0g/kg yeast supplemented diet had significant effect on whole-fish body composition except for the moisture content. This was attributed to increased fish appetite due to the yeast supplementation. After challenging the fish with A. hydrophila, the fry fed with yeast supplementation especially 5.0g/kg had low mortality as compared to those fed with control diet. Similar observation has been made in several fish species such as Labeo rohita (Chandra et al., 2006), Piaractus mesopotamicus (Hamilton et al., 2017), Orechromis niloticus (Sherif et al., 2019; Dawood et al.,2020).
Several studies have enumerated the benefits and mode of work of prebiotics. Google scholar indicates about 18,300 research articles from 2000 to 2024 on beta-glucan alone use in fish. The use of prebiotics has therefore been identified to boost growth, feed conversion, improve health status, increase stress resistance among others. The factors influencing the effect of immunostimulant application can be dosage, length of application, mode of application, stage of growth of fish and health conditions of fish.
More research is needed in the African context on the extended effects of prebiotics in larvae, the dosage and the best modes of application to elicit the needed response.