When I recently cycled my nitrates were at 5.00. I added 4 zebra Danios and 2 baby Peppered Corys. Ammonia and nitrites are still at zero. I did a 50 percent water change yesterday and nitrates are now under 5 and maybe even close to zero. I did not vacuum nor change any filters. My tank is 75 gallons. Also I did a fishin cycle. I have 12 zebra danios, 6 Platys, 4 Corys and 1 Mystery Snail.