Hey guys i have a 125 gallon tank with a couple peacock bass that i am planning to breed my question is does sand HAVE to be the substrate or does gravel work too im asking this because i know once you remove the substrate the cycle is no longer there so you must wait for the cycle to return with the new substrate but while im waiting i will have nowhere for my fish to go until its ready. So could someone help me out im confused on what to do.