Two mangrove species Avicennia marina (Forsk.) Vierh and Rhizophora mucronata were selected to study the development of the seedlings under different salinity and growing media. The seeds were grown on soilless (water) and soil (sand) medium, with different water treatment, T1, T2, T3 and T4 (0ppt, 15ppt, 25ppt, 38-40ppt). Roots initiation, length, seedling height and survival were observed. The study shows that theres a statistically significance (p-Value of 0.039497) on the sapling development of R. mucronata and A. marina grown on salinity of 15ppt under soilless media, and theres no significant difference in root development between 15ppt, 25ppt and 40ppt. As comparison between A. marina seeds grown on soilless and sandy soil media (treated with water from T1, T2, T3 and T4) the height of the seedling grown on sandy soil treated with T1 tank (freshwater) has a statistical significance (p-Value of 0.0002071) difference compared to seedlings treated with T2, T3 and T4 (15, 25 and 40ppt). In conclusion, the two mangrove species show significant seedling development on a soilless media under water treatment with salinity of 15ppt.