My brother dosed several of his tanks with flourish excel a couple of days ago. Well, I think he overdoses then because all his loaches were dead, including two khulis in his 90G. He lost six sidthumunkis, striatas and some barbs. In another tank four swordtails died and two cories. Could this be caused by an overdose of excell? I don't think he could have overdosed the 90, but the kuhlis died. All the shrimp survived. Any thoughts.