where the does piranhas breed if its all sand? im askin cause bout a week ago 2 of my piranhas just start'd getin darker/purple, there about 5 1/2 ~ 6 inches not realy sure, but does 2 seem to be a bit more aggressive after couple big stroms i been havin, and if it is a sign of breeding i have bad news, i have to go on a trip so imma let my friend hold my 5 p's. n im pretty scared he mite kill it =X sigh... is there anyway i can find out if they are a breeding pair? n if they are is there anyway i could make em continue after i come back? please reply asap