l boughtblank deck off a guyand it was supposed to be a fish and it wasnt anyone knw if l can still put the fish tale on? its a 6'8 and l was hoping to cut it down a little 3-4 inchs

l really do not understand ur question. If the blank is wide enough & thick enough for a fish shape, they u should not have a problem with the tail. The two tips of the fish tail radiate from the center out. If ur blank is wide enough, cut it to size & then form ur tail inware. Be careful when u shape ur wings that one side is the same as the other. l usually cut the shape while the tail is thick & then shape it down with my sureform to the right size.

Hope this helps

Snake

Snake has it dead on again! One more thing, if you have a wood stringer, be carefull how your cut that into the apex of your swallow tail. Lots of fish blanks have split stringers because of that. If your want, you can ADD a stringer, but that is getting a little complicated. Good luck!
http://surfersteve.com/glosscoat.htm

Print out your template for your fish and just play with it on various points of your blank to see where it fits best. If it is a traditional fish you will probably want it as far back as possible to keep your rocker flat. Hardest part about a fish is the damned butt crack. Take your time with it. The best place in the word for shaping advice is swaylocks.com. It is a BB for shapers.