 The slender rainbow sardine is primarily differentiated from the rainbow sardine, because the slender rainbow sardines do not have tiny radiating striae on the posterior part of their scales.There is some indication that the slender rainbow sardine may tend to have more vertebra than the rainbow sardine.Originally restricted to the tropical and subtropical portions of the Indian Ocean and the South China Sea, the slender rainbow sardine is found off shores from Taiwan and the Philippines, to northern Australia, to east Africa, Madagascar and into the Red Sea.