Catastrophe with Corcoran Grant aquarium

I would second the sabotage comment. Kids seem to enjoy these things. A chemistry teacher briefly kept a marine aquarium but discontinued when kids would do things like pour in HCL...etc.

Yeah, I was just thinking that something doesn't sound quite right with your situation. Let me see if I have these facts straight:

1) The tank was set up in early October and had at least a few fish in it since then
2) You used a little native substrate.

My thinking is that this tank really ought to have cycled by now, especially since you introduced bacteria via the substrate. I'm really suspicious that something other than ammonia is causing your problem. Something via the cleaning guy, while it sounds unlikely, seems more likely to me than ammonia. Or it could be something that we aren't yet thinking of.

Could the power have gone out over the weekend? Is it possible that you forgot dechlorinator/dechloraminator and you left the office right after the water change? I'm thinking that something caused mass distress. My guess is that one fish dying didn't cause the whole cascade, because shiners are so good at cannibalizing each other.

A puzzle, this is.

I agree, I'd question the cleaning person, if it's possible. I've had shiners die in aquariums, and they just get eaten. I don't have die offs. I know it happens because sometimes I find small bits of what's left.

I agree, I'd question the cleaning person, if it's possible. I've had shiners die in aquariums, and they just get eaten. I don't have die offs. I know it happens because sometimes I find small bits of what's left.

I wouldn't discount an power outage.

I wouldn't discount an power outage.

True. That would do it also.

Likewise, I'm available to help get the tank back up and running again.

Using some native substrate will definitely help with the cycling. I can also supply some gravel out of a well cycled tank if you need it.

The eclipse hood completely covers the top of that tank, so cleaning contamination is unlikely. Sabotage is possible, but again, unlikely.

For what it's worth, I use Seachem Prime as a water conditioner, and don't really do anything else to my water. No ammo-lock, no carbon filtration, or anything like that. In our area, all municipal water is surface water with very similar properties to stream water. (Of course, you know that better than anyone!) So I don't do much to it.

Thanks for all the suggestions. To answer the above question, yes this the same tank I had the yellowfin shiners.

Another possible scenario- one of my co-workers told me that the Friday evening prior to the die-off, the cleaning person was vacuuming the office with a busted bag on the vac. According to my co-worker the whole office was filled with a dense cloud of dust. This co-worker then got onto this cleaner's case about being an idiot and making the place messier than he found it. My co-worker then left for the weekend. The cleaner was the last person in the building until the following Monday, when all the dead fish were discovered.

Not enough evidence to convict, but it makes me wonder...

I didn't mean to suggest that the cleaning staff did anything intentionally. But maybe they were using some sort of cleaner in your office that made it's way into the tank somehow - by surface contact, or even being sucked into an air pump.

I also had this thought - check and see if any other maintenance things were going on over the weekend. Exterminator? HVAC cleaning? Spraying for H1N1? Any construction? You get the idea.

It is with heavy heart and much confusion that I report that the over the course of this previous weekend we experienced 100% mortality in the Corcoran Grant-funded native fish aquarium. I am at a total loss as to what happened. Maybe you all have some ideas.

Some background- its 40 gallon tank with an Eclipse hood/filter and small powerhead, pea gravel substrate, and two large pieces of resin driftwood for decoration. No plants. Three dimensional silicon "faux rock" background.

I started conditioning the tank in early October with a couple of yellow fin shiners. On October 26 the tank was stocked with locally collected fish. The total fish population was:

2 stonerollers
3 turquoise darters
3 yellowfin shiners
2 Ocmulgee shiners
1 rosy face chub

Temperature stays around the mid-70s.

I've been having some problems with ammonia over the last few weeks and have been testing the water daily. Ammonia levels were hovering around 0.25ppm. I've been doing 25-50% water changes at least weekly. In the last 2 weeks I've been using Stress-Zyme hoping to encourage the biological filtration. On Friday I did a 25% water change and also dosed the tank with Amo-Lock in an attempt to suppress the ammonia since I was not going to be back in the office until today.

The fish appeared healthy and not at all stressed when I left on Friday afternoon. The yellow fins were even doing their breeding behavior for the first time since I've had them. Monday morning I got a call that all of the fish were not only dead, but in a rather advanced state of decomposition on Monday morning. The office was unoccupied all weekend to the best of my knowledge.

I want to collect some more fish and start over, but would like to have some idea as to what went wrong so as not to repeat this unfortunate occurrence.

Any ideas?

Very sad situation indeed, after reading the other posts I will relate a my own personal story; I once took a biology class in high school in which I was the sole long-haired juevenile delinquent in the class, as such I was always getting in trouble for making wisecracks,coming in late or not doing my homework. My chair was in the back of the class not far from an aquarium filled with cichlids and plecos, the teacher had no idea that I actually read the text book and enjoyed nature and its inhabitants; one day while sleeping through a lecture on something I had already read in the book I was woke up to an angry teacher accusing me of killing the fish in the aquarium with bleach (something I would never do.... the fish and the field trips were the only reason I ever showed up to class!). I ended up being told to clean the aquarium and when I refused (I didnt kill them) was sent to the assistant principles office and kicked out of the class. I later found out that it was one of the straight A teachers pets who did it to impress a girl who had a heart made of cold rock, and when retelling the story laughed about the whole ordeal. I would not rule out the janitor and I would suggest setting up a hidden camera (I have no pity for people who kill pets or wildlife for no reason).

Thanks for all the input!

Well, I'll be putting locks on the hood this time around. I've removed the tank to a "less public" area while I get it going again.

Hopefully I'll post some pics of a healthy, happy aquarium in a public area sometime at the first of the year.