Effect of Ulva lactuca and Sargassum cinereum Supplemented Diets on Growth Performance of Koi Carp (Cyprinus carpio Linnaeus, 1758) Fry in Laboratory Conditions

There is a potential to formulate cost effective aquafeeds using seaweeds in the littoral zone of the coastal belt of Sri Lanka. This study was designed to evaluate the effect of seaweed supplemented diets on the growth of Koi carp. The experimental set up consisted of a control (C) and two experimental treatments (T1 and T2). The control diet (without seaweed) and the two test diets, of which 30% of the weight of control diet was replaced by Ulva lactuca and Sargassum cinereum were fed to Koi carps in C, T1 and T2 respectively. Proximate analyses were carried out for both ingredients, and the diets were prepared following standard methods. Koi carp in fry stage belonging to the same cohort (weight 2.20±0.08 g, length 3.89±0.04 cm) were assigned to C, T1 and T2 in fiber tanks filled with 150L of water (n=20 per tank) with four replicates each. The fish were fed 5% of their body weight twice a day (09.00h and 15.00h) for 14 weeks. The length and weight measurements were recorded once in two weeks. Fish performance was compared using Body Weight Gain (BWG), Daily Growth Rate (DGR), Relative Growth Rate (RGR), Feed Conversion Ratio (FCR), Feed Efficiency (FE), Fulton’s Condition Factor and survival rates. At the end 14th week of the experiment, mean values of the weight, length, BWG, DGR showed a significant difference (p 0.05) among treatments. There was a 100% survival rate in all groups. Aquafeeds supplemented with seaweeds showed promising results in terms of increasing growth rates of young Koi carps.