Aliasing tailfin → tail_fin
Link to alias

Reason:

Same thing, seems in common enough usage that an alias would be useful.

Related implications

• arm fin → fin
• elbow fin → fin
• membranous fin → fin
• notched fin → fin

Related aliases

• torn fin → notched fin¹
• damaged fin → notched fin¹
• shark fin → fin

¹ Fits the standards seen in the notched ear alias tags + is used occassionally