Fishing

http://www.panafishing.com/index.html

https://www.facebook.com/Playavenaofishing/

http://www.xn--islacaasmarina-vnb.com/index.php?page=fishing

http://www.casalajagua.com/activities/

Contact one of the tour companies above if you are interested in a chartered fishing trip.  You can also hire a captain from Playa Arenal for a fair price which can include all equipment.