My yellow tank's top fin is all spiked. The first 2 or 3 sections are together then there is a rip or missing fin to where when he raises his top fin up only the first 3 or so raise and the others can't because they are not connected. He looks great other than that as well as the other fish. I'm guessing he either tore it from fighting when I introduced my threadfin or it's from my water being far from perfect --- I really need to get a ro/di.
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90 gallon with 26 gallon sump/refugium, 2 x 250 MH lighting, 100lbs live rock, 1 - yellow tang,1 damsel, 1 - cleaner shrimp, 1 - coral banded shrimp, 3 - emerald crabs, 2 - porcelin crabs, 6 - peppermint shrimp, 1 - green ricordia, 1 - toadstool, 1 - brittle starfish, 1 - sand sifting star, 100's baby feather dusters,Ass mushrooms, frogspawn, xenia, 1 clam,
6 - Leather coral, Green star polyps,Lime green/orange button polyps,1 huge carpet anenome,various snails/hermit crabs | 
what's eating my tang?? 
