Help! Foxface dying

[barry cuda]

I've had a 4" foxface in the 100g display for about a month now. He seemed fine until this morning...I found him stuck against the teeth on the internal overflow box. Obviously, this isn't a really huge current, so I assume he's very weak if he was stuck there. I gently pushed him off the box with an algae scraper and he drifted with the current, not swimming, until he found his way to the bottom of the tank at one side. He's sitting down there now, breathing heavily and looking very dark in color. He's nibbling on the hair algae on the rocks next to him, but hasn't bothered to move at all even for the strip of nori 2" from his head. His caudal fin has a couple 1/8" chunks out of the back edge. The only thing in the tank I can think of that could do that is the hermit crabs.
I think he's dying. He's gotten stuck a couple other times in the last two weeks - once pinned against a rock by the return output, once stuck to the "cage" on a powerhead intake. I am wondering if he sustained some kind of internal injuries during one of those events. He looked fine after both of those (we turned the offending device off to let him swim free) but he sure looks awful this morning. Anybody have any ideas other than letting him sit and see if he revives?
Almost forgot - parameters are near perfect. Ammonia 0, nitrite 0, nitrates about 5, pH stable at 7.8, temp rock-solid at 80, SG also stable for the last few weeks at 1.024.

 

[shawnhardy]

I am not sure what could be causing this to happen to your foxface but your pH should be between 8.1 and 8.4

 

[barry cuda]

I agree the pH is low, but it's been stable at 7.8 since I set up the tank...all my sources agree that it's acceptable in that range as long as there aren't any big swings.

 

[greatfullreefer]

As long as the PH is a stable and consistant 7.8 there will be no problems. PH swings cause problems.

 

[bang guy]

Do you now, or have you ever had any other high activity fish in your tank?
Do you have a skimmer?
What is your water turnover rate?
Is there any covering on the tank or film on the water surface?

 

[barry cuda]

I have a Euro-Reef skimmer operating in the sump and pulling out good, dark skimmate. Turnover is about 12-13x water volume, including the overflow/return and three powerheads. The only covering on the tank is eggcrate to keep the kids' fingers and toys out. There's no film on the surface - the HOB overflow seems to do a great job of preventing this. The only other fish in the tank are two young Banggais, maybe about the size of a silver dollar.
I just found the foxface stuck to a powerhead again maybe an hour ago. I immediately unplugged all the powerheads but he just sank to the bottom. I thought he was dead until I went to gently scoop him out with a net, and he fled the net into a cave in the LR. Now he's lying on his side in the cave, not really moving except to respire quickly & shallowly.
??? I have no idea what's going on. Everything else in the tank looks like it's just fine...snails, hermits, Banggais, xenia, everything looks healthy.

 

[barry cuda]

Well, he died. I saw he'd swum out of the cave and was lying on the sandbed in the front corner of the tank. As I watched he twitched a few times, then turned very pale, went stiff and his pupils dilated & fixed, and he sank all the way onto the sandbed.
#$#@!%!!!!! I'm so discouraged right now I don't know what to do. I would feel better if I had any freaking idea what he died of, but I just don't have a clue. I'm really wanting to just tear down the whole damn tank. It's a cyano- and hair-infested nightmare anyway.

 

[thedraven]

Sorry to hear about your foxface. Im suprised and puzzled to hear about the problems youve been having with your tank. Ive checked out your site several times for reference for my own tank, and its been an excellent help. Dont get too discouraged, your other fish are doing fine? How long had you had the fox? What else do you feed besides nori? Your ph is a liiiittle low, but it really shouldnt have affected him. My ph tends to dip to a similar and stable level and my fox has been alright so far.

 

[barry cuda]

It was definitely discouraging me earlier today, but I think I've managed to snap out of it. This just comes on top of some casualties due to stupid mistakes I've made in my nano...I killed some xenias by underestimating how fast conditions would change if I changed the equipment setup. At least I know what I did wrong there, but still, it's frustrating. The fox looked perfectly fine & healthy until this morning. The $30 I'm out stings a little, but that's not as bad as just having a creature under my care die for reasons I can't explain.
Besides the nori I feed the tank on mysis, which is mostly for the Banggais but everyone likes it, and homemade food from Robert Fenner's recipe. I'm cutting back feedings as of today, along with leaving the lights off for a few days, to try and deal with the hair and cyano. We're continually adding to the cleanup crew too, so I hope to have those issues under control soon.
Thanks for the words of encouragement. It helps to hear things like that when you're down in the dumps.