African Chilid Fighting

hey i recently got 2 african chilids a dark blue one and a bright yellow one not sure what species but the first day they were fine together and also on the second but then they started fighting and then the yellow one pretty much ripped of the blue ones tale fin and top fin apart. P.S now hes digging up the aquarium and moving allthe decoration around and theres a rock that is much bigger then him and he was able to tip it over and dig under it and make a cave. the blue fish is still alive and there almost both the same size but the blue one is a lil smaller.

[Rip's Girl]

Ah, you're seeing how fun AC's can be. I have 18 of them. They're really aggressive...

The yellow one is a male, no doubt. The digging is something you'll have to get used to.
Does the blue one have stripes on it, even subtle ones? If it does it's probably the same species as the bright yellow one. (I had some of those a couple years ago.)

You might want to get 2 (big) rock caves and put one on either side of the tank. (What size tank do you have?) Then they will both stake out their territory and probably won't be beating each other up as much.