New Blue Platy Dropped Dead...

Hey everyone.

I just got home from work to find one of my new platies was dead. I only got this blue platy (and another one, white orange and black mickey mouse) 6 days ago. She'd been swimming around fine, not clamped up, although she hid a bit, I assumed she was just settling in. The only unusual thing I had noticed was the alst few days she hadn't come out to eat, or she'd go up to food but then not seem to eat it. When I first brought her home I'm pretty sure she ate. Thought she was looking a tiny bit skinny, but again, I thought it was just a settling in thing. She was the smallest platy in the tank, but by no means a TINY fish. She was not being harassed by other fish. There was no fungus or other growths on her, I had a bit of a look when I took her out.

I got these two female platies because I only had 3 others (1 male, 2 female) and 2 were ganging up on the third one - who was depressed and clampy and sick looking as a result. In the last week I was really happy because my unhappy one made best friends with the mickey mouse and is completely back to normal. Water stats should be fine, they've been fine for weeks, and I do a weekly 30% change. But I will check them again now to be sure. *Edit* Just checked, are fine, ammonia + nitrite are 0, nitrate - 20, ph 7.2.

What could have possibly happened The mickey mouse platy came from the same tank at the LFS so should I be worried about my other fish??? They all seem fine at the moment...

Somewhat random but probably entirely unrelated - when I was looking in there were loads of tiny bubbles (I assume they're bubbles) in some of the higher levels of some of my plants - at first I thought they might be dreaded snail eggs but when i disturbed the plant they all just floated to the surface and popped. Just thought it was a little strange as I've never had random bubbles appear before...

Here's some shots I took of her probably three or 4 days ago - and one comparing her with my other platies.






I'm really sad. I just don't know what went wrong!

Sometimes it just the stress of the move.
How thin was she as being very thin can point towards flukes, tb, to internal parasites which livebearers have.

Not heaps thin...I mean not a huge difference to what she looked like up there. I guess I'm used to most of my other platies looking huge because they're pregnant most of the time...

I took care to acclimatize and everything...I thought they would die like the first couple of days, not 6 days later... Like I said, she had been mostly normal, except for being a bit shy (but still came out sometimes, not a complete recluse) and then the lack of eating last 2-3 days.

It could of been a number of things hard to say bless her.
R.I.P.