foxface rabbit fish looks like he broke his tail

[aquadummy]

so today my foxface rabbit fish looks distressed. when he ate this morning he wasn't swimming fast like he normally does and then has been swimming erratically. his top half is all black now. at night he gets black and splotchy which is normal, but never during the day. also his neck of his tail has a couple red looking spots and he seems to not be using it. i checked the water and everything seems fine. no ammonia, no nitrite, and about 10 nitrate. ph is at 7.9 which ive never been able to get any higher. its a 30 gal sw tank with about 5-8 lbs of live rock and we've had him for about 6 months. his tankmate are a fire flame angle, scooter blenny, 2 cleaner shrimp, and a spotted mushroom. they all get along fine. plus my foxface is the biggest. all they other fish seem to be just fine so i don't think anything is wrong with the water. from my best guess it looks like he might have gotten his tail caught on something. any ideas or help would be greatly appreciated. i can post a video if that will help

 

[melosu58]

This is what I`m observing. First the tank is too small. It needs to be at least a 75 gallon tank. From this link you can see that. Smaller tanks can speed up diseases and illness by adding stress to the fish. Also your LR amount is pretty small. These fish need plenty of caves and holes to hide in. IMO more LR is needed as well as a bigger tank.

 

[Innovator]

Red spots are normally bacterial related, but imo the video shows a common display from seeing its own reflection. It is hard to decipher if there is an actual conditioning problem. Get us close up pictures, but as Melosu said you will eventually need a larger tank if not already.