Kappahycus alvarezii is a species of seaweed belongs to Rhodophyta class which is commonly cultivated by coastal community in tropical areas. This research therefore aimed to clarify the growth of K. alvarezii thallus from culture tissue and cloning selection cultivated using horizontal net. The method was an experimental design, which used a randomized group and Specific Growth Rate (SGR) analysis. Horizontal net was used to avoid pest attack and research failure. The results showed the total growth rate in average within 40 days from the initial 20 g growth to 120,1g and 139,7g of cloning and tissue culture seed, respectively. Meanwhile, the average of SGR of tissue culture and cloning were 6.3% and 6.7%/day, respectively. Statistically, the cloning selection method and tissue culture were not significantly different with good maintenance, especially using the horizontal net. Transparency level had a positive correlation with the growth of cloning selection seeds.