I have 2 senegals that are 6" long, they have never even glanced at another fish untill today. One of them took out a 1" Tiger Barb (just added today), he couldn't swallow it so he spit it back out but the Tiger Barb was already dead. He does not attempt anything on the two 4" Guarami's or two 2.5" Rosey Barbs that have shared the tank with him for about 4 months.