Personally, I think it was stress. He was eating great when I put him with the marbles. Then stopped eating. The whole front of his disk pattern seemed to melt, like candle wax. Left him in there for two weeks and never started eating. So I took him out and put him back with the female and treated both him and her with two full cycles of Metro and Prazi with daily 50% water changes and adding new meds each day for the next month. Still never ate. About a two weeks ago he started twitching and darting aimlessly and I new he was not going to make it, then last week I noticed the back of his disc would start to curl then lay flat back down. Yesterday he was curling, darting aimlessly and twitching all at once and new he wasn't gonna make it another day. Went to lunch with my wife and came home and dead. I really had a bad feeling when he went in the main system and the front of his disc looked like it melted it wasn't a good sign.
Marbles are doing great. Back to eating normal. I won't add the female flower for a while yet. Gonna get her on a multiple of foods before even attempting.
Would you acclimate her to the new system or just dump her? The water params are essentially identicle, even the temps.