Tank of 4 years--All of the fish suddenly died?

[Zach Vs Ponies]

It's been four years since I first set up my first saltwater aquarium. It is a 60 gallon. My first fish was a yellowtail damselfish, and my second fish was a yellow tang. Over the years, I've lost many, many fish. Most were due to my error and stupidity. A few years back, I lost all but three of my fish in a matter of weeks.. But I've never lost them all.

Last evening, I fed my fish. Everything was fine. None of my fish showed any signs of disease or anything... they were all swimming perfectly fine. Today, I came home from school to notice that they were all missing. Slowly, one by one, I began to find all of their dead and dying bodies (Two of these included my first two fish, a yellowtail damselfish and a yellow tang--Broke my heart). The showed no signs of disease, except the stress a fish would resemble when something went terribly wrong. I was wondering if any of you could help me find what failed terribly? Here was my livestock (As of last night):
Ocellaris clownfish x2
Yellow Tang x2
Yellowtail Damselfish
Blue damselfish
Cinnamon clownfish
Sixline wrasse
Cleaner Shrimp
Blood fire shrimp

As far as I can tell, all of these fish (Except for the two shrimp) are dead or missing (The Sixline wrasse is probably dead in the LR). I understand that the tank is way overstocked, but it has been this way for quite awhile now. The nitrates are a bit high (80 ppm). The temperature is 77 degrees F. The salinity is 1.022. The pH is 8.0. Of course, as already stated, the tank is four years old, and is well cycled and such.

I have two other tanks (A 55 gallon seahorse tank and a 20 gallon tank where my corals will be going). All of the fish in these other two tanks, which are completely separate, are fine.

My plans from here are to tear down the tank and just start fresh. My LFS has a 125 gallon tank for sale, which my dad wants me to get. As I have already said, I know my tank was way overcrowded, especially with two tangs. Whenever I go to re-buy my livestock (ughhh!!), I know I will want a tang. This 125 gallon will be much roomier for him/her.

Thank you for any help you can give me. I know this is a bit hard to judge with the lack of pictures, which I will work on getting.

[Fish Bowl]

The one thing I'm wondering is this since it's not quite clear (to me at least), but are your shrimp still alive?
There's plenty of possibilities as to what may have happened really but a quick guess based on what information I have would be there may have been some hydrogen sulfide trapped in the sand bed from 4 years from "possible" lack of adequate care that was "possibly" released by some heavy vibrations to the tank recently, or the wrasse dug up a good amount somehow.
Nitrates in what seems to be a FOWLR of that size with that type of stocking is actually not THAT terrible (of course .10-.40ppm is better) but depending on your tank husbandry it "seems" plausible that your sand bed is moderately deep and has been left undisturbed for such a long period of time (aside from a worm population in the sand that can't get everything) = the origin of high amounts of the toxic gasses.

And once again, this is all just a wild guess based on whatever I could infer from the information given so until more information is given, just take this as a grain of salt or sand if you prefer that. (It could very well be velvet that was introduced into the tank via a new wet addition or some crazy chain reaction resulting in oxygen deprivation or many other possibilities.)

[showcasec6]

You need to check all the parameters. Do you have phosphate issues? While it may not kill your fish, it could stunt growth and possibly stress them.
If your parameters seem OK then:

Are your inverts OK?
Do you have any coral/macros that seem to be doing well?

If all else seems to be OK in the tank, I'd look for odd/rare things like stray voltage in the tank, as I have seen that kill fish in a reef while the coral were relatively OK.

Also, check to see if anything has dropped into the tank, any corroded metals, chemicals, etc.

[macman7010]

Zach these parameters would help is diagnosing the cause of your tremendous die-off:

Phosphate Level
Nitrite/Ammonia, (even a cycled tank can have something weird happen that raises ammonia)
What you were feeding your fish

80 ppm in the nitrate zone is high, even for fish. Oddly enough I would have thought you would have lost your shrimp long before you lost any fish. There are a multitude of reasons issues like this can crop up. Typically I would rule on a parasitic infection, this could be internal or external. Have your fish been thin and pooping what looks like a while piece of string? Fish will often eat even with an internal parasite though without antibiotic soaked food it can kill them. Internals even spread to other fish. External parasites I would think you would have noticed.

[Zach Vs Ponies]

Thank you everyone for your replies. Firstly, I'd like to apologize for the lack of information. I was very upset & crushed after yesterdays events, and I really didn't even feel like thinking about anything "saltwater" other than what the heck was going on with my tank. I'd also like to announce a piece of good news: My cinnamon clownfish and ocellaris clownfish... They're alive and swimming now (They were never dead, of course. Lol!). I am currently treating them with the only thing I have on hand (Melafix Marine). Here's something else I need to ask: I know I need to remove them from this tank. Should I put them in an empty (no water at all) 10 gallon I have (Take water from my DT and put them in there with a filter & heater), or should I put them in my biocube that is cycled and ready to put fish in it. I know that sounds like a dumb question, but I still need to treat them both.

I would also like to introduce another interesting piece of information that I didn't include yesterday. As I said in the original post, my livestock is: 2 Ocellaris clownfish, 2 Yellow Tang, Yellowtail Damselfish, Blue damselfish, Cinnamon clownfish, Sixline wrasse. Out of all of this livestock, the two damsels, the 6-line wrasse, and one of my Ocellaris clowns were the smallest fish in the tank. Here's what I found interesting (I don't know if it's significant). When I got home, my larger-sized fish were still breathing, but obviously dying. The smaller fish (Two damsels, clown, and wrasse), though, were all dead. Like I said, I don't know if that's significant, but it might could play a role in something.

Now, to answer everyones questions:
Yes, the shrimp did survive. There was a scarlet cleaner shrimp in the tank and a blood fire shrimp. The blood fire shrimp was alive yesterday, but when I went to capture him and move him, I couldn't find him. I think he went into hiding. I captured the scarlet and it's now in a tank by itself. Surprisingly enough, I also found another interesting find. A few months ago, I bought a peppermint shrimp. I lost it after about a week, and I figured it was being eaten inside of the rock work. This morning, I found it moving around the tank. Also, I have a starfish inside of the tank, which is still alive.

I do have corals as well. My zoanthids seem to be doing well. I have some ricoreda mushrooms that also seem to be doing well (Besides the fact they're mushed up because I have the lights off!). My xenia's, unfortunately, seem to be lifeless.

My most recent addition to the tank was a bubble coral, which I added this saturday. It didn't come from a system with any fish in it.

The tank was well oxygenated in my opinion. It had a large sized pump (Not sure on the make or model.. Got it used), and a Maxi-Jet Pro 900.

Now showcase6 introduced a rather interesting question. "I'd look for odd/rare things like stray voltage in the tank, as I have seen that kill fish in a reef while the coral were relatively OK." Whenever I first saw my tank, my mind immediately went to this. Is there any way to check if there's voltage in a tank? This weekend, I put my right hand in the tank, and I thought I felt something shock me. I blew it off, because I stuck my other hand in there and didn't feel anything. It only seemed to happen to my right thumb (I know that sounds crazy.. but it's the truth).

And, finally. My fish looked fat and healthy on Sunday night, the last time I saw them all alive and healthy. They did not look thin. I remember on that Sunday afternoon, my friend came over and saw my fish eating something weird looking. I looked, and I knew that it was their poop. Their poop was not stringy. It almost looked like flake food whenever it was pushed apart by the current in the tank. I feed the following things: instant ocean marine gel blend, OSI spirulina flake food, freeze dried cyclops-eeze, julian sprung's sea veggies, ocean nutrition formula two flakes, and a frozen marine blend (brines, mysis, etc. all combined). The OSI food, cyclops-eeze, and julian springs sea veggies I got in the mail the other day, and just started using these recently. On certain days, I'd feed each of these foods separately. Sometimes, I'd mix a couple of them. Also, on some days, I'd mix a tad bit of everything.

Now, finally, parameters. Keep in mind that these parameters might be a tad bit off from what they were yesterday. There's a couple of dead fish that I can't locate and a couple that I can't get to until I get in there and get the tank emptied.

EDIT: Parameters will be in the next reply. I really wanted to get this posted so someone can answer my first question. It's the most urgent one at the moment. Here's it again: "Should I put them in an empty (no water at all) 10 gallon I have (Take water from my DT and put them in there with a filter & heater), or should I put them in my biocube that is cycled and ready to put fish in it. I know that sounds like a dumb question, but I still need to treat them both. "

Thank you all SO much for your replies and your hopeful future responses.

[Tin_Whistler]

Now showcase6 introduced a rather interesting question. "I'd look for odd/rare things like stray voltage in the tank, as I have seen that kill fish in a reef while the coral were relatively OK." Whenever I first saw my tank, my mind immediately went to this. Is there any way to check if there's voltage in a tank? This weekend, I put my right hand in the tank, and I thought I felt something shock me. I blew it off, because I stuck my other hand in there and didn't feel anything. It only seemed to happen to my right thumb (I know that sounds crazy.. but it's the truth).

If you don't have a GFCI get one now before doing anything else to your tank. Water + electricity isn't something you want to "guess" on and hope it's not an issue.

If there's not electricity, and enough oxygen in your tank there's not a whole lot we can tell you without peramiters. (i know you said those were forthcoming already)

Also, I don't think your mix of fish is appropriate for that size tank. Yellow tangs get too big, the paired clownfish will own most of that tank, and the other clownfish going to be the third wheel... The third angry wheel. Also other damsels are highly aggressive.

[showcasec6]

The "shock" story is the same I heard from the reef keeper that had a fish crash (corals and inverts survived). I haven't tried this, but was told by electrician that a voltmeter you can get at HomeDepot etc. will tell you if there is current in the water. To register small currents you have to get a GOOD ground, because any current at all can affect your fish (even a small amount). I realize it seems rather anecdotal, but it's worth checking out to spare your livestock. Also, if you find a bit of current, don't just throw a Ti grounding plug into the tank. Figure out what's leaking current and remove it. Basically, unplug one device, test for current, unplug the next etc on down the line until you figure out which device is the culprit.

My LFS (not sure if I'm allowed to post a non-supporting business, PM for detail), dealt with this as well, and found that his pump somehow had corroded in a manner that was putting current into the tank. He can tell you more, if you'd like.

One other thing:
This is a rather unlikely occurrence, so I'd make sure everything else is right with the tank as well. That said, this is fairly quick to check with a voltmeter so it doesn't hurt to see.

[Zach Vs Ponies]

Hello everyone. Well, I've been busy at work during the past few hours since I posted. When I last posted, I had just found that two of my clownfish were alive and seemed to somewhat be responding to treatment. The clownfish, my corals, and two shrimp have since been moved to a quarantine tank. The clownfish posed a problem while catching, and I got really frustrated. As I have already said, I had already made plans to take the tank down and go for an upgrade in size. I decided to completely tear down the tank. All of my live rock is being stored inside of empty aquariums/bins until I get my new tank in (Of course, they're receiving filtration, heating, etc.). The two clowns are also doing surprisingly well.

Being stupid, I put my hand back in the tank earlier and I felt the electric current again. I turned off all of my pumps, heater, and everything and I knew I had to tear down the tank. Unfortunately, I was stupid and didn't take the water tests until I took all of my LR out of my tank and it was a bit of a mess (The tank is still with water, just no animals). Here are the results I got:

Nitrite-0ppm
Phostphate-.5ppm
Ammonia-A bit above 0.

I know that some of these results don't seem quite right, but I have learned that this probably isn't the problem. I checked the sump area of my tank (My tank has an "In tank sump"), only to find my heater cracked and full of water. So, I have a feeling this was the problem.

Though, I can't completely blame the heater. It is my fault and stupidity for allowing this to happen. I fully admit that I didn't carry out my tank duties as much as I was supposed to, and this is what I get. As I've already stated, I'm looking in to a new tank. This tank will have a protein skimmer, proper filtration, more live rock, an EXTERNAL sump, and the most expensive heater I can find.

If any of you have a response to this, or still don't think this is a problem, I will be keeping up with this post. Please feel free to post :)

Again, I thank you all for your replies and future replies.

PS: While I was cleaning out my tank earlier, I found all of the missing and dead fish that I lost yesterday. RIP: "Tang", "Little Tang", ocellaris clownfish, six line wrasse, blue damsel, and yellowtail damsel("Sammy"). Not only these, but I also found my Blood fire shrimp dead as well.