yeah meat, plants, insects and seafood(this will probably drain first cause a lot of dergs tend to eat this)
also your male got really lucky colors/ genes, i got some ugly mustard dragon when i started lel
to get food, just check all the boxes for said page in your Hoard (there is a quick button on the page that looks like a V mark that selects everything) and then press convert :3 Then you can feed from the lair