Vacation Ammonia Spike, Please Help

[FishySarah]

I returned from vacation tonight to find four dead fish in various stages of decay in my 29 gallon tank and one fish dying. All of the dead fish and the dying one were platys The rest of my fish, the 4 neons, 5 tetras, the three remaining platys (one adult and two fry) 2 molly fry, and 4 barbs, looked awful.

I immediately tested nitrites and ammonia- nitrites were fine but ammonia was through the roof. I did a pwc the day I left and readings were fine then. I think what happened was one fish died, and was left to rot in the tank, and it caused a chain reaction- as the ammonia levels rose, more fish died leading to a further rise in ammonia, etc. I was gone a week so there was plenty of time for this disaster to happen. BTW, my tank runs a Whisper 30, temperature at a constant 78 and has been set up for one year, with no other fish deaths in the past three months.

Well, I did my 80% water change, I have the dying fish isolated in clean water but I'm sure its too late, he is really bad off.

My question is, is there anything more I can do to help my remaining fish recover? Like add aquarium salt? I am keeping the water as clean as possible.

 

[Puffdaddy]

I think the first thing we have to do is find out why the fish got sick and died in the first place. However I do agree that the decaying fish is the direct cause of the ammonia spike.
1. what did the "awful" looking fish look like? >what are the symptoms
2. did any of the fish seem to be acting weird in any way before you left?
3. how were the fish fed over the week span?
4. any other related info you can give no matter how insignificant?

I'm sorry for your loss

 

[FishySarah]

I think the first thing we have to do is find out why the fish got sick and died in the first place. However I do agree that the decaying fish is the direct cause of the ammonia spike.
1. what did the "awful" looking fish look like? >what are the symptoms
2. did any of the fish seem to be acting weird in any way before you left?
3. how were the fish fed over the week span?
4. any other related info you can give no matter how insignificant?

I'm sorry for your loss

1. The fish was curled up and lying on its side, every now and then it would try to swim and I could see it breathing really fast. It is still alive but doesn't seem to be getting any better.

Now my adult molly is sick. She seems to be having difficulty keeping herself upright and is gasping at the surface

2. Now that I think of it, they were. The platys were staying in one corner and gasping a bit at the surface. Since I always feed in that corner, I assumed that they were just looking for food. Now it seems omonious because the molly is gasping at the top.

3. I had a vacation feeder in the tank, the kind that dissolves and releases food. It is now half-gone.

4. I do not have a nitrate test kit, so there is a chance there is an issue with this. Before this, I had no problems in the tank and no fish deaths in the past three months. I did use a new dechlorinator for the water change before I left on vacation- I had to buy a new bottle. I picked it up at petco and it is the same brand I have always used. No- it can't be the decholorhinator- I used it on the other tanks and those fish are fine.