yes i they are als ocalled disco fish if you have got one then you might not want to buy more but for the ones you have they will sometimes get agressive if there is some way to seperate them it would help say a divider or a seperate tank. both are comunity fish so i would have thaught they where not terratorial tho if they are then perhaps breaking up the aria with plants and orniments that would obstruct the veiws of the fish and offer cover for the guppys. how big is the tank?