Effect of seaweed, Kappphycus alvarezii fermentation by various fermenters combinations as thickener on gel strength, attractiveness and palatability of gel diet in Tilapia, Oreohromis niloticus

Gel diet is one of the aquaculture diets that use seaweed, K. alvarezii, as a thickener made with cooking with water contents of between 50-70%. One effort to increase the nutritional content of seaweed is fermentation. However, fermentation affects the attractiveness, palatability, and gel strength of aquaculture artificial diet. This study aims to compare various fermenter combinations that are most effective in fermenting seaweed, K. alvarezii meal in terms of attractiveness, palatability, and gel strength. This research was carried out at the Laboratory of Nutrition and Feed Technology, Faculty of Marine Sciences and Fisheries, Hasanuddin University, Makassar, Indonesia. Experimental fishes used were tilapia size 7, 15, and 28 g. Various combinations of fermenters as treatment were seaweed meal without fermenter (treatment A), + 1.5g Bacillus sp. (treatment B), + 1.5g Bacillus sp. + 1.5 g of Rhizopus sp. (treatment C), + 1.5 g Bacillus sp. + 1.5g Saccharomyces sp. (treatment D), and + 1.5g Bacillus sp. + 1.5g Aspergillus sp. (treatment E). Fermentation is carried out on an an-aerobic basis. The parameters measured were attractiveness, palatability, and gel strength. The experimental design used was a completely randomized design with 5 treatments and 5 replications. Data were analyzed by ANOVA and W-Tukey test. The results of this study indicate that the attractiveness and gel strength of the experimental diet were the same in all treatments (p>0.05), while the highest palatability of the experimental diet was obtained in the experimental fish that consumed D diet, namely seaweed meal fermented with 1.5g Bacillus sp. + 1.5g Saccharomyces sp. Based on the results of this study, it was concluded that tilapia, which consumed the gel diet, contained seaweed fermented with 1.5g Bacillus sp. + 1.5g Saccharomyces sp. has the best palatability.