There’s no intelligent native species in the whole system, and absolutely no animal life of any kind on Cetus Beta itself. The entire world is devoid of any animal life, but completely populated by many forms of strange plant life, some of which look a bit like animals at first sight. The planet is mostly water with thousands of islands all over the planet, most in long strings or chains.
In 2370, Keiko O'Brien decided to have her class visit the planet as it was just about the safest planet ever discovered, and it’s been checked out by two Federation science vessels and declared absolutely harmless. Unfortunately a team of Cardassians were stationed there attempting to locate several escape Trofars. They attacked the shuttle carrying the teacher and her students, but thankfully survived the crash on Cetus Beta. With the help of the Trofars, the castaways overpowered the Cardassians and escaped back to Deep Space 9. (DS9 novel: Field Trip)