I've had 12 neon tetras for about 2 years now, and within last 2-3 months I lost 3 of them. I check my water parameters every two weeks or so in my tank with neons (30 gallon) and they're stable, no ammonia and nitrite, but nitrate is always within 10-20 ppm. I perform weekly water changes of about 30%, vacuuming the gravel with each water change. I really don't think there is anything wrong with my water. The pH is also stable, always around neutral (sometimes it will be slightly above or below 7.0). For the last 2-3 months, however, I'd be finding one dead neon at a time, usually sucked against the filter intake tube. It's not the filter's fault, as my neons never had a problem resisting the filter's water flow. What do you think could be causing these deaths? Or maybe neons live that short in aquaria? Or ... could it be my golden algae eater killing them at night perhaps? But I really don't think he's doing that - I NEVER see him chase my neons, not even my angels (which are quite large fish). I don't think the angels are killing my neons either because if they wanted to "hunt" for my neons, they'd eat them and not leave them to float dead, freely around the tank. Any ideas?