I have three goldfish. I'm pretty sure one is a girl and the rest are boys. But I have noticed something my goldfish who is the biggest is doing. A few weeks ago, I heard him jump once in the tank. Then a week after that, he did it three times in a row, hitting the top of the tank and hitting his head. He has not done it ever since but today I saw him not really biting, bu putting is mouth on the female, and just now I saw a red spot which I think might be blood. I'm really scared that my fish will die. Please help!