I just re-stocked my tank using Bio Spira. I have a 37 gallon, and it is cycled, but it only had 4 serpae tetras in it. I added 5 Black Phantom Tetras, 8 Cardinal tetras, a Bristlenose, and 1 long fin tetra that wouldnt stay out of the net while she was getting the fish I wanted so she just gave it to me. I added bio spira, and then I added the new batch of fish. Hopefully everything goes well and all levels of everything stay where they should. I'll be keeping an eye on my new babies!