Q:

What determines how strong a fish is?

Occasionally while fishing, I will get a message like this:

What affects these events?  Do all instances of a single fish type have the same strength?  How can I lower the chance of these happening?

A:

A fish that is too strong for you is a direct result of you not having enough Fishing Power to do so. 
You gain Fishing Power for, you guessed it, fishing more. So the more you fish, the more likely you have of catching harder fish, and more profit.
I am certain of this, as well as the fact that some fish are harder to catch than others. I experimented with this for a bit, and the fish that I got when I used the minnow for bait were a lot harder for me to catch then the ones I get by using the worms for bait. When I increased my fishing level I caught the Small-mouth Bass Fishes more frequently.

