I'm afraid you need to make sure your ammonia and nitrites are zero while the nitrates should be below 40 ppm.Maybe these are the levels needed for the gars to breed? Not sure.
I'm afraid you need to make sure your ammonia and nitrites are zero while the nitrates should be below 40 ppm.There is already a sign that you must either upgrade your filtration system or move some of your fish to a larger or another tank.