A Muckdweller's muckdweller

[Rickshaw]

I recently discovered that Muckdwellers are a playable race. I've also heard tell that they are usable as familiars, though I cannot find where. If anyone knows what the bonus for having a muckdweller familiar is, and what book it's listed in, I can live happy.

[Zaq]

Same book as the Muckdweller itself: Serpent Kingdoms. They're not a standard familiar, but they're a valid option for Improved Familiar, assuming that you hit the caster level and alignment requirements (which are 5th level and within one step of LE, respectively).

It's all there on pg. 146.

[Coidzor]

Muckdweller wizard with muckdweller familiar and muckdweller wizard followers with muckdweller familiars. Entire tribe of muckdwellers.

though, if one could find a way to make a muckdweller wizard one's familiar...