My fish are dying mysteriously!!! Help!

I had 3 serpae tetras, 3 zebra danios, and 1 cory cat, and now, all of the danios + 2 of the serpaes have died. I don't know why they are dying. Before they died, they had a red patch on their sides. The day before or so nothing is noticeably wrong, but before they die, they have a red patch on their side and lie around lethargically. They all died within days of each other. Is this a disease, or some toxin in the water? My cory cat seems to do fine. But I'm not sure what will happen to my last serpae.

Might it be the water cleaners in the water? My city added chlorinimate (sp?) to the water. It's been at least 3 months, and I didn't get any conditioner that gets rid of that. Do you think that it might be that toxin that is killing the fish? Or some disease? I did add a bunch of anacharis that was in a tank full of feeder goldfish, but the anacharis is doing fine. Maybe it's carrying disease?

Can anyone help me please?!

Well, I'm not sure, but I've been using the same water source (the bathroom faucet) and there has been no problem for more than 2 years. What disease does the red patch indicate?

If it is a plant carrying a disease, do you think it would have affected the fish sooner rather than in a few weeks?

And if it's the chlorinimate (sp?), would it affect the fish right away or kill slowly?

Thanks for your reply. I'm hoping that the problem is the chloramine, since I wouldn't want to disinfect the whole tank because of a disease. I'll try to get some de-chloramine solution this week.

How much would a water test kit cost? Is there one that does everything like metals to ammonia to nitrates and pH, or are they sold seperately?

Kasakato said:

Just waht you need Click Here. This is the best kit I have ever used, and its super cheep. It includes everything you would need for a non planted tank.

Click to expand...

Would it be accurate if I had a planted aquarium?

So do you guys think it's the chloramine not disease right?