I wasn't sure if I should post this in the discus section but since my question really isn't fish specific I didn't think it would be that much of a difference. I recently aquire some great 3-3.5 inch discus. i checked on them before going to bed last night and they were at the top of the water gasping for air. Ran all the tests (ph/amonia/nitrite/nitrate) and they all checked out. I did a 30 percent water change and very reluctently went to bed. I woke up this morning and checked again. Same thing, fish at the top of the tank. Again checked everything and did a 30% water change. any ideas what might cause this? Thanks!