I isolated him with extra air, it helped for awhile, but he's not moving much now. I have 3 loaches who are fine, my params , ph, everything tests great, I think he had and internal problem, either he's too little for crickets or yesterday a black bulge showed up at the edge of his eye, like internal bleeding. I know he doesn't fight, I think medical, but the timing with the sand change is wrong, he quit eating before I did that. Probably a big world for a baby little fish, may he go in peace now or pull out like a true champ cause waiting is killing Me.