Pleco's Dropping Dead!

[mikeyy_lol]

I bought 3 small bn plecos a week and a half ago and they were doing fine, when I first got them they were lighter which I expected as they would be stressed, they were all eating and showing no symptoms. 2 of them went black with the spotty pattern on them a day or so after I got them so I presumed everything was going great and went out to the LFS a few days ago to buy a pair of apistos. They both seem fine still and eating and the lighter pleco is quite shy compared the the other 2.

Now I wake up this morning and saw one of the plecos laying on the sand. Dead. I had no idea what caused this and checked the stats. 0,0,<20.
Went to university and came back and another was dead! Checked the stats and still exactly the same! I'm actually extremely puzzled by this as there have been NO symptoms at all!

Does anyone have any idea what it might be?

 

[mikeyy_lol]

Anyone?

 

[Embrace]

How did you cycle your tank?

 

[Lolly123]

Need to know a little more info in regards to your tank. What are all your parameters like? What is your setup like? and as Embrace asked, did you cycle it?