I'm too lazy to keep a chart. Instead I use ladycfii's method of stick with one fish, breed an entire tank with that one fish, put an ! next to the pregnant fish's names so as to keep track of which ones would lead me in a circle, and then sell the pregnant fish once they give birth. Once I feel that I've gotten all that I can out of that one breeding fish, I'll replace it and start the process over, adding a @ to the fish's names and will continue like that until I have finished.

If you're wondering about my labeling system, I just follow the order on any QWERTY keyboard:
! @ # $ % ^ & * ( )
1 2 3 4 5 6 7 8 9 0
You could just use numbers if you'd like, but for some reason I can remember the symbols easier. Go fig.
HTH
-spaceman