I have a 50 gallon tank. I have two comet goldfish (one orange and one white) and one rosy red minnow in this tank. I have had these fish for two years now.
I know my tank is a little too small. I am saving up for a larger tank but I have recently run into some unforeseen flooring issues that have put these plans to a temporary halt.
I call them Yin and Yang (and "that little rosy-red minnow"). The white goldfish is a big bigger than the orange one. A little fatter in the belly area while the orange fish doesn't have that "fat" look. Could that mean male and female?
Now, details out of the way..
These two fish chase each other around the tank all the time. It is usually the smaller orange goldfish chasing the larger white goldfish, but it goes both ways. They have done this for as long as I can remember (and the rosy-red minnow sometimes chases both of the goldfish around, but not often). The reason they got the names Yin and Yang is because they often start to chase each other at the same time and spin in circles together. My question was this: is this behavior normal for goldfish? Could it be a playful behavior or an aggressive one? I have also read that male goldfish will chase female goldfish around during the mating season but this "chasing" doesn't even seem to stop, even though I keep the tank at a constant temperature.
Edit: I have noticed that they have both lost a couple of scales on their sides, although I haven't noticed any damage to their fins. I can't help but wonder if this is because it is aggressive behavior or if it is from rubbing up against each other a lot?