Fish/Cories dying!

[keithk831]

A couple weeks ago, we added some guppies to our tank. Ever since then, we have had 2 cories, one platy, and 2 guppies die. The tank did go through a mini-cycle, but the ammonia and nitrite levels never got too high. I also did a few water changes during this time to keep the levels down.

I'm not too concerned with the guppies that died, since they were new. I am concerned with the cories. Before this happened, one cory died right after laying eggs. I think she died because the tetras were nipping her fins trying to eat the eggs.

Next, another cory died. It was laying on the bottom of the tank, with its barbels practically gone and white eyes. Then, we found a guppy dead, then a platy dead. Platy was floating on the top of the water, and the guppy was face-down in a fake plant leaf.

Later, we had another guppy die (on Thursday I think). Today, I found another cory behind a plant dead on the ground. Its fins were partly shredded, and yesterday I noticed it had what looked like white, flaky skin near its dorsal fin. She was pretty active the other day, so I dont know what the problem is.

Water tests are fine, and all other fish are healthy. What can I do to stop more deaths?

[keithk831]

Today, another platy died. It's like these fish are dying without warning! I can't see anything wrong with any of them. Even upon examining the dead platy I can't really see anything wrong. I went and bought more test strips today and everything looks great. I also started using Jungle Lifeguard tablets. It's supposed to treat everything. We'll see.

It says on the package it's "Not suitable for scaleless fish". Think I should isolate the cories? I don't have another tank, but I could put them into my CD tower case (round clear plastic) i've been putting eggs into and let it float in the tank. But it'll be 6 days. The tablets float on top of the water in a mesh thing, so they aren't on the bottom of the tank or anything.Thoughts?

[Lotus]

If your water checks out, I'd assume some kind of disease. It could be either bacterial or possibly viral.

I'd recommend trying Maracyn Two (antibiotic), which generally works well on systemic infections.

[Pure]

I wanna know why your tank had an ammonia spike after adding guppies. That shouldn't happen. Is this tank still pretty new? Did you change or do something different?

Cories won't tolerate any traceable amounts of ammonia.

But yeah if the ammonia and nitrite are both at 0, and have been for a wile, and fish are still dying. I would follow Lotus's advice.

[keithk831]

Adding more fish to a cycled tank will put it through a min-cycle while it gets used to the heavier bio-load. It didn't really get past .02ppm, so it was at "Alert" on the dial.

The tank has ben cycling for a couple months now. I did replace the filter and do a water change a couple days before adding, the guppies though. Shouldnt have made a huge difference though.