An Etymological Dictionary of the German Language/Rogen
Rogen, m., ‘roe, spawn,’ from the equiv. MidHG. rogen, OHG. rogan, m., for an earlier *hrogan, mm.; also MidHG. roge, OHG. rogo, m.; corresponding to the equiv. OIc. hrogn, n. plur., AS. *hrogn, E. roan, roe. Goth. *hrugna- is by chance not recorded. The true source of the word cannot be found; some connect it with AS. hrog, ‘nasal mucus,’ others with Gr. κρόκη, ‘pebble,’ Sans. çarkara, ‘gravel.’