I'm heading down to Marathon Key for my spring break and have borrowed a speargun from a family freind. This gun is about 20 in overall and is powered by two bands and has a 4ft line which i am thinking about making longer towards maybe 10 ft. I am woundering what size of fish I should be able to take with this rig. I was thinking about some snapper around the reefs, maybe grouper if i can find some, maybe a medium sized 'Cuda for shark bait, idk. Any suggestions on any of this?