You gotta tip toe like a slinky weasel behind the Shadowcat's tail as it slumbers, resist the urge to hug the fluffy murder kitty, and feed it a tasty basket of sardines from your hot bar. The kitty accepts this generous gift and disappears in a flash.
So my dad didn't know that they could swim or go invis. P.s. he has played much more than me, so when I went to tame one he got confused and asked why. When I showed him it's ability he was astonished because he didn't know they could swim that fast.