Excel is extremely toxic whether you're talking about shrimp or fish. It can be used, but I'd worry about excel 100x more than ferts.
FTR I have Amano shrimp, and I dose EI, and at one time I used excel. I've had the shrimp swim right into the excel cloud while I was spot dosing, and they showed no ill effects. That's different then having a high level in the tank though, to which they would be constantly exposed. I dose extra iron in my tank in addition to regular traces (including copper) and have had no problems. Amano are much hardier shrimp than most of the coveted ornamental species (CRS etc.) from what I understand. I believe it also, as they seem to be very tough and forgiving of water quality.
FTR I have Amano shrimp, and I dose EI, and at one time I used excel. I've had the shrimp swim right into the excel cloud while I was spot dosing, and they showed no ill effects. That's different then having a high level in the tank though, to which they would be constantly exposed. I dose extra iron in my tank in addition to regular traces (including copper) and have had no problems. Amano are much hardier shrimp than most of the coveted ornamental species (CRS etc.) from what I understand. I believe it also, as they seem to be very tough and forgiving of water quality.