How many Fish Inches in my Tank

[FanOFish]

Before anyone tells me I have too many fish because clown loaches can grow to be 14 feet long in a 2 month span I have a serious question.

I have a 42 gal. hex tank which I believe will hold fewer fish than a regular rectangular tank because of less surface area. With that in mind, would someone look at the fish in my signature and tell me how they would calculate the fish inches I have and the max you could have in this tank.

I'm not planning on adding any new fish I am just curious. The two clown loaches I have are about 1.5 inches long not counting their tails. The pearl gourami is the largest fish at about 2 inches.

Thanks