About two months ago I bought a 55 gallon fish tank. I did the normal procedures of getting the rocks and running the equipment and all that. For awhile I wasn't getting any ammonia, which i assume is normal. Many of those fish died and now I have 1 tiger barb and 4 zebra danios. My problem is my tank wont cycle. I've been doing 15% water changes for about 4 weeks now and I'm still having ammonia and some nitrates but no nitrites (which I don't even know how thats possible). I figured by now my whole tank would be complete but its not even to the nitrite part yet. The good news though is that the rest of my fish haven't died. There is this orange dark colored stuff on some of the decorations in the tank. Does anyone know what this is? All and any help will be much appreciated. Thanks-