As some of you know, I lost power in my fish room a few weeks ago, and had to move the rays into the house. They are currently in a 100g, 60x18" tank

3x a week, 50% water changes. Eheim 2 Pro for filtration(stacked with Matrix), plus the big sponges. I have a spray bar on the powerhead, which is on a timer, blowing waste in 1 hour intervals 5 times a day. (less stressful for the rays, IMO)
Ever since I put them on this barebottom they have been eating krill like crazy, and already showing dramatic improvement. Before the 'emergency' I had been starving them to try to get them to eat pellets, so it was very bad timing. The tank temp in the fish room dipped down to 68 degrees, and they were okay even after the transfer, ate krill immediately..
I transfered them into the new tank, and the smallest ray, "stumpy", got her disc nipped by a hungry albino bichir. I also had to remove the gravel while they were in the tank, and it got really nasty.. No problems. Even was dumb and left the glass heater in their, got a little heater burn, no problems, healed right up.. These rays are pretty tough LOL
Current tankmates are a Jardini and Ctenopoma also.. soon to be no Jardini, all Ctenopoma..
