I've been overstocked in my 29g brackish tank for a while, with a figure 8 puffer, a big molly, a baby molly, and four knight gobies (that's the bad part). I kept rescuing them from the LFS 'cause they kept getting them in, and not selling them. So anyway, I thought nature had finally paid me back by killing off at least two of them, maybe as many as three. So tonight I decide to redo the look of my tank, and I take out ALL the rocks, and what do ya know, FOUR GOBIES! It's unbelievable. I've tried to setup the tank so that four will be happy, with a huge system of caves that they could get lost in and not find each other for a while, and I provided some more interesting swimming space for my puffer I think... As soon as the tank settles down I'll grab some pictures.