What animal the word 'tachash' refers to is a matter of some debate. According to the Babylonian Talmud and Rashi's commentary, the tanchash was a kosher, multi-coloured, one horned desert animal which came into existence to be used to to build the Tabernacle and ceased to exist afterward. The King James Version of the Bible translates the word tachash as badger. Another hypothesis is that the Hebrew term "orot t'chashim" refers to very fine dyed sheep or goat leather, hence the Jerusalem Bible translates the term as "fine leather". A currently popular hypothesis is that the term "tachash" means dugong. This translation is based upon the similarity between tachash and the Arabic word tukhas, which means dugong. In accordance with this hypothesis several translations, such as the Jewish Publication Society translation, render tachash as dolphin or sea cow.
Tachash from Wiki.