What did you use for substrate? You may or may not get a cycle, but 4 days is not enough time to tell. IMHO, return the tang and shrimp and give your tank at least a few more weeks to do what it may do, if anything at all. Also, adding a YT should be done as a last addition. There is also QT'ing before adding new fish. Its up to you, but IMO its just too fast to move. I know its hard, but worth it. I lost a few $50 fish due to not finding this board, hope I helped some.