dwarfgourami
Fish Connoisseur
I can understand about your boyfriend not being keen on bettas; they are rather different from other fish, either you like them or you don't. Shrimps and ADFs are good ideas, unless he specifically wanted fish.
Other possibilities are:
endlers - they are smaller than guppies but closely related
pygmy rasboras- small schooling fish
pygmy corydoras- move all over the tank unlike peppered corys
I agree with catxx that peppered corys would only work while they are very small; peppered corys grow to between 2 and 3 inches (females equally get up to 3 inches) and are extremely active at times, they shoot around the tank at great speed. I keep mine in a 19 gallons and think of that as a bit of a minimum. And I wouldn't advise you to buy fish that you can't house once they grow up. Guppies are smaller but still very active fish; I wouldn't keep them in under 10 gallons. It is possible to keep mixed sexes, I do, but only of you have the space to play around with and preferably more than one tank so you can separate male and female fry.
Other possibilities are:
endlers - they are smaller than guppies but closely related
pygmy rasboras- small schooling fish
pygmy corydoras- move all over the tank unlike peppered corys
I agree with catxx that peppered corys would only work while they are very small; peppered corys grow to between 2 and 3 inches (females equally get up to 3 inches) and are extremely active at times, they shoot around the tank at great speed. I keep mine in a 19 gallons and think of that as a bit of a minimum. And I wouldn't advise you to buy fish that you can't house once they grow up. Guppies are smaller but still very active fish; I wouldn't keep them in under 10 gallons. It is possible to keep mixed sexes, I do, but only of you have the space to play around with and preferably more than one tank so you can separate male and female fry.