yeah, definitely look into that white growth; that is NOT normal (!?)
on the whole Dempsey + Convict relationship, I had an 8" male dempsey and 5" male convict that were absolute best friends, always hanging together, never fighting . . . then the convict got sick (I quarantined him, treated him, but he eventually died), and the Dempsey got sullen and mean after that . . . he got traded in to the LFS
who knows, maybe they bonded . . .