Two of my goldfish look beat-up and I don't know who's doing what! Help!!!?

Question

I have 3 common goldfish in a 20 gallon tank. This morning I was feeding them and I noticed one (the smallest) has red blotches near his mouth, back, and stomach, appearing to be blood. He seems to be acting OK, though. One of the other goldfish (the medium sized) has one red mark on his stomach, but he is acting very strange as he is just sitting on the bottom of the tank, not moving much. And the other one (the biggest, but normally the most timid) looks and is acting fine. A strange thing I noticed is that normally the small one & the medium sized one are normally together, while the big one normally just hides in a log. But today, the small one is sticking close to the big one and they are both swimming together and hiding in the log together, while the medium sized one is all alone sitting on the bottom of the tank. Please help! I don't know who is doing what and who I should seperate! Right now I'm planning on moving the medium sized one to a fish bowl. (EDIT- WAIT FOR MORE)

Answer 1

I am not a fish expert but I think I know the answer! I don't think anyone is harming your goldfish. I think that since you have three of them and, two of them are injured that must mean the third fish is harming your other fish. The fish that looks normal must be a meani-bobini-slowvini! I hope that helped!

Answer 2

The best way to find out what is going on in your fish tank is to view it when you are not there. Fish can be like children. They will be little devils when your not there , but when you are watching them they act all innocent. Remember while you are watching them they are also watching you. They are not doing what they usually do when they do not have to pay attention to you.

So your options are to get a blue light or something that illuminates the room close what it is like when you turn off the lights but still allows you to see what is going on inside your tank.

Spend a lot of time in the room with the tank to the point where you are not a distraction to the fish. This is not always a full revealing of what they do.

The best way is to setup a video camera and film the tank for long periods of time during different times of the day. That also  includes the night. I have found this way to be the most revealing way to see what is really going on inside your tank.   It can be something to try just for curiosity purposes. To see how the mice play when the cat is away, so to speak.

Answer 3

seperate the one you think is doing it, ten if it continues, do it to another one, and another one ect. until there is only 1 left that you haven't seperated yet.

Answer 4

There is always an chance that the goldfish just couldn't handle it and attacked from etheir fighting for food or cramped space or. I might suggest try at least having more space for them to at least swim around. that could always be from an bite mark, it should heal up relatively fast observe them from an distance to see they're habits, and then take action.

Answer 5

Your tank is too crowded. 20 gallons is minimum for 2 goldfish. You need atleast 30 gallons for 3 goldfish. Because of being overstocked they are competeing for food and space, and the largest one is being dominant because of his/her size. Get a bigger tank and DON'T use a fishbowl, thats just a disaster waiting to happen.