Sorry, but I cannot stop LOL. That orange fish u see is a Red Devil, they have flesh ripping teeth & he gets goldfish as a snake every few months. Hes also almost a foot long. he is a mature male & he's mean as a guard dog!!!

He tried to kill me on a daily bases & I cannot put my hands in the water & I have to keep this big rock ontop of his tank lid so he cannot splash water all over my room & jump up to bite me. His teeth act kinda like a sharks jaw. He openeds hiw mouth & when he bites down his teeth come all the way outta his gums to spike his pray, or to scratch the tank glass

heheh, here is a close up of his mouth, I don't think ur goldfish has these needle sharp black teeth..


Now as to sex the fish, good luck at that size

wait until he gets about 6 inches long & then its easy to tell. If the fish has a hump as a forehead, its a male, if its a smooth curved forehead, its a female.

Male Hump


Female Curve