what kind of fish do i have?

Question
I have a killer goldfish! It has a like sheild that comes out at the bottom of this neck when he is going to attack or is angry. He has killed every kind of fish that I have put in my tank besides an allgy eater who will fight him back.I know for sure its not a gold fish need some help on what type it is.maybe i can but some more of its kind so he wont kill everything moving!?

Answer
Nate, please send me a photo.  I can help identify your fish.  Goldfish do not kill other fish.

I would check water quality, as it's usually the cause, not the fish itself.

I look forward to your information so I can better help you.  Provide an image and I can take a look for you and let you know what kind of fish it is.

Sincerely,

Renee