I've been getting this sickness for two of my male nanochromis. And several other apistos. All which have passed now. However, it is only apistos and my nanochromis, my rams seem to be doing fine in the tank. The only difference between that tank and others is it is dirted and is capped with sand. Any issues with this sand causing diseases? https://www.homedepot.com/p/Cemex-50-lb-30-Mesh-Sand-200000278/100321932 Its weird since these fish can go fine for months and then out of the blue contract a disease and die off. This time the nanochromis seems to have a large bump on its head, I have moved him from the sand in case that was the causing factor.