Hi,i planned to add some nice and quite big peaceful fish to my tank,i want to add chinese hi-fin shark.but when i went to the shop to buy it,i saw all of them are under 10 cm.i kinda not sure if i want to mix it with my other fish since all of my fish are 14 cm above and are semi aggressive fish.but the shopkeeper mix them with bunch of 20 cm paddlefish and three 25 cm sturgeon that i don't know what species they are and they are doing well.can i put the chinese hi fin with fire eel,chalceus,frontosa and bichir?