Is this too much?

Nope....

Have a breeding pair of cons in a 10gal.

Yeppezs....

most likely, i would say yes. convicts usually dont grow too large, and would have enough room in a 20g im think.

however, their have been a few pics of some old, rather large convicts. If i recall, i think someone has an old guy on here thats 5-6" or so. if they get to that size however, i may start leaning to them needing a slightly bigger tank.

it can be done, although if one decides to beat up the other, there's nowhere for it to go.

yeah you could do it if you keep on track with the water changes most cons will never get past 5'' there are some that reach the 6''-7'' mark so i guese it depends but you'll be fine for a long time