1 1/2 inch is all you need. Most likely was clogged in the procedure described. Just use your syringe plunger with a little water in the syringe and it should blow it out. Remember also, with the bigger fish you may have to move a little further back to the anal vent-middle of the dorsal fins with your line of travel being the same as if it were a smaller fish. Just follow that line, middle of the gill plate and middle of the side fin, needle halfway in between and follow that line back to that so to speak crossroad ! Hit it everytime with a big un' ! Hope this helps ! Oh, and get any bigger length wise and your needle will hit the other side of the rib cage and foul almost everytime as well. And you don't want to be hitting any vitals or vessels with your normal 45 degree angle towards the head.  Of'course, all this hinges on going through the side. I didn't even ask. LOL.

Oh, and yes,  I was talking through the side.  Thanks.