Hey, thanks! I'm glad you enjoyed it. Yeah, it tends to feel much better in motion.
Fish size 10 is quite a monster. It probably dragged you forcefully into the uncharted waters
. Note that you can assign villagers to help anchor the harpoon. This is helpful if you're into big fish harpoon-hunting for sports. Every involved villager can reduce fish's pull significantly.
The biggest fish I've encountered was 7. Theoretically, they can go up to 20. As mentioned before, I used Gaussian distribution for fish generation. Bigger the fish - rarer its occurrence. As with the real fish.
In my experience, the easiest way to catch big fish is with hooks. Hook handling takes a bit od practice and you need to have sufficient number of hooks, but hooks are the most efficient weapon against big ones. Villagers can help here too. Each adding 2 additional hooks to your arsenal.