Thanks for the comments - I'll try to answer questions asked . . .

I never noticed any type of aggression in the tank - the glowlights seem to be very passive, peaceful fish. I did add the 6 julii corys to my regular tank without QT (due to an unfortunate accident with my QT - the corys were on order & came in; had problem w/QT & LFS wouldn't hold fish for me). These were wild caught corys; my suspicion is that they had "something" that spread throughout the tank. I did have a very slight nitrite spike due to adding all 6 corys at once which I controlled with daily water changes. Nitrite spike lasted approx. 4 days ~ .25ppm.

About a week after the corys were added, I noticed a few of them flashing on the sand in the tank. Several days later, a few of the tetras were flashing, as well. It was at this time that I slowly dosed tank with 2 tsp per gallon of non-iodized salt for possible ich/velvet. Also raised temp to ~ 82. Kept the tank dosed with salt for about 3 weeks, then it was slowly removed by daily PWCs. The fish stopped flashing & I thought problem had been adverted.

A few weeks after the salt treatment, the first of the corys began to fall ill. They became very lethargic, stopped eating, began wasting away, got very pale, then were unable to maintain an upright position & developed the red speticemia streaks on sides & fins. Not all fish fell ill at once - I lost the last cory about 5 weeks after the first one had fallen ill.

The tetra symptoms were a bit different - they seemed to go from being totally fine to being unable to maintain upright position, spinning, & got very pale. I did not observe any popeyes or pineconing with the tetras I lost over the summer. Time period between onset of symptoms & death was only a matter of hours. I finally began euthanizing the tetras as soon as they began displaying signs of illness because I had been unable to save any of them & couldn't stand to see them suffer.

I nearly gave up the tank at that point, but hung in there & was finally satisfied that my sick fish days had ended . . . now this! I'm quite discouraged again. I have a 135 gallon tank to set up & don't want to do that until I'm sure that I can keep fish alive in a 29 gallon! Thanks again for the help!