Saki hikari are sinking sticks. Suitable for fish of 3cm and more (as mentioned on the packing) I got my saki hikari from xian leng in seksyen2 shah alam. They are the main distributor for hikari foods. Visit them at their website for more information.
www.xianleng.com. Notice that some 88 marine shop also sells that but are very fast selling. As for which types of food for ryukins some are the sifus here might be able to help you.