Golden zebra loaches have ocular barbs that are hidden by a fold of skin. They pop out when stressed or for defense(like a switch blade). It may have jammed these in the mouth of the other fish to keep from being eaten. You will have to gently work it out or bigger fish will be lost too. There is no other way that I know of.
Originally Posted by Benjamin1990
It has swallowed a very small golden zebra loach. I tried to pull it out but I ended up braking its tail off.