Cichlids hitting sand on side

[jcunningham0295]

I need some help, I currently have a 75 gal with electric yellow, rusty's, hap morri, red empress, german red peacock, flameback, and electric blue alhi. I noticed lately since I moved them from a 55 gal gravel based tank to my 75 gal sand based tank that they are hitting the sand on their side more often. I check my water and everything looks to be ok, except my nitrates were about 40ppm so I did a water change as well. Now I noticed some of the demonstrating breeding bechavior as well and one of my female electric yellows is holding. Is this behavior normal?

[Lisachromis]

The scratching on the sand is a sign that the nitrates are high. It could be for other reasons, but often the nitrates is the main one. The behaviour seems normal to me. Just make sure you keep up on your water changes and they shouldn't "flash" (scratch themselves on the sand) anymore.