I posted in your dirty tank thread.
Your oscars aren't happy because they're crowded and in their own feces. Two oscars will get too big (and probably already too big) for a 50gal.
On top of this, you use river rocks as your bottom. The **** will get stuck in there and will pollute the tank. You don't vaccuum your tank, which causes the water to have a whole bunch of nitrate and ammonia levels. Go to the LFS and get your water tested, watch as your nitrate / ammonia levels are through the roof.
Get proper substrate, get a bigger tank, do more maintenance changes, clean your filters. Your fish are dying at the bottom because you're neglecting to properly house and clean them.
Your oscars aren't happy because they're crowded and in their own feces. Two oscars will get too big (and probably already too big) for a 50gal.
On top of this, you use river rocks as your bottom. The **** will get stuck in there and will pollute the tank. You don't vaccuum your tank, which causes the water to have a whole bunch of nitrate and ammonia levels. Go to the LFS and get your water tested, watch as your nitrate / ammonia levels are through the roof.
Get proper substrate, get a bigger tank, do more maintenance changes, clean your filters. Your fish are dying at the bottom because you're neglecting to properly house and clean them.