I am a new fish owner, having bought 3 juvenile oscars previously in the last 2 months. I had moved my oscars into my (don't hate me) clean, unused spare tub from their original 10 gal. It's only temporary; I have a 75 gal on the way next week. I decided to buy 2 plecos to go in the 75 when I get it; in the meantime I put one in the tub with the oscars and the other in the 10 gal with my feeder goldfish. This evening the pleco in the 10 gal was dead, but he wa fine this morning before leaving for work. My other pleco in the tub is fine. I had the water in both tanks tested before getting the fish, both were fine except the ph was slightly high in the 10 gal. I added a teaspoon of aquarium salt to adjust it. So other than the fish being ill from the lfs (they were in separate tanks in the lfs), I have no clue why it died. By the way, I bought the plecos this past Saturday afternoon. Also, my feeders were fine in the same tank. Any advice would be great. Thanks, Tom