Our Swordtail Died

We just got some new fish last weekend. And its strange, out of all of them, the swordtail seemed really healthy and energetic.

But...he's now in fishy heaven. :(

I got home last night and saw him zoom to the top for air, like he REALLY needed it. I thought that was wierd cause I thought they got air through their gills. We fed them and later I noticed him at the bottom of the tank, almost like he had to fight to stay there. Then, I walked by again and saw him stuck to the filter intake. :( He got loose and I saw that the end of his tail looked like he had a beginnings of ICH, his eyes were bulged and he already had a bruise on his side from the filter.

Poor little thing. We also got a gold/orange Molly from the same tank and she seems really lost without the swordtail. Poor thing.

Any ideas?? The Ph is fine, temp is fine.