Tetra/Cherry Barb Massacre

Hey guys, I know a lot of people may think that the thing I did was very stupid, and yes I know that it is but please bear with me.

I have a tank with 2 bichirs (Senegal and Endli) One black frontosa Cichlid, and one crayfish (Dont know what breed, but is black in colour, and has white pincers)

I wanted to try to get some fishes with bright colours so as to make the aquarium more colourful. Since my fishes have not exhibited aggressive behaviour, I thought that I could try adding Cardinal Tetras and Cherry Barbs into my tank

I added these fish into my tank, and after going out for 4/5 hours, I came back and realised that 15 out of the 20 Tetras & Barbs were gone, probably eaten.
So now I'm thinking of getting rid of some of my large fish, (probably the cichlid) But i just want to get an opinion, who(One/some/all) do you think is the culprit? So that I can sell it off or give it away to make room for other smaller fish.