Bolivians are very peaceful. The only problems you might run into is aggressiveness between themselves. They won't bother any other fish.
It's GBR's that have pink bellies. For Bolivians, it's near impossible to tell until they mature. Females will stay a little smaller, and won't have the long extensions on their dorsal fin and tail fin.musho3210 said:i think (notice the think since im not sure) females have a pinker belly and they their dorsal fin is smooth at the end. But i dont think you can tell unless they are older and close to mating