CA glue is 'super glue', otherwise known as Cyano-accrylate. It comes in a few viscosities: thin, medium, and thick. Thin dries / cures almost instantly, while the thick may take a minute to set-up.
You can aslo get a 'kicker' whic is usually a spray to 'instantly' cure teh CA glue.
But they are brittle. Ans the larger the gap, the weaker it'll be.
Keeping the CA bottle in the fridge will prolong it's shelf-life.
Epoxy is stronger, only in that is is not brittle, and somewehat plyable. Longer cure epoxy is stronger then 'quick cure' (5 minute) epoxy.
I would use teh CA to tack the fins in place, then use epoxy for the fillet. (or use white glue, or 'aliphatic resin' (yellow carpenter's glue) for the fillet)