Oranda goldfish

Question

The bump  

Side view   Hi, I have 1 oranda goldfish in a 10 gal. tank.  This morning when I fed him (Nutrafin MAX goldfish flakes or sometimes he gets wardley goldfish flake food) he looked completely fine but when I got home from work he had a white lump on the right top side of his head.  I gave him a bit of food and he ate like he normally does and he's acting normal, swimming a lot.  I clean the tank every few weeks(it gets a lot of green slime all over the walls and rocks) and do 40-50% changes every week or so.  I use an Aquaclear filter for a 20 gal. tank.  I don't have a thermometer but the water is room temperature.  I got him a few months ago from a friend so I don't know how old he is or how he lived before.  Up until now he has seemed healthy, and he still seems happy.  Should I be worried?

Answer
Bailey,

When you say you clean the tank every few weeks, do you mean you take the fish out and clean the gravel and decorations, replace the water, and put him back in? If this is what you are doing, stop doing it. Every time you do that, you remove the beneficial bacteria that he needs to stay healthy.The ten gallon tank is too small for your goldfish. I like to explain it this way. You have a ten gallon tank that holds approximately 10 gallons of water. Then you add 1 inch of gravel. That takes away 1 gallon of water space. Now your goldfish is swimming approximately 9 gallons of water. Once you add the filter, you are losing approximately 1.5 gallons of swimming water. When you add all the decorations, you are losing approximately 2 to 3 gallons of swimming water. When everything is in the tank, your ten gallon aquarium is holding approximately 5 to 5.5 gallons of water. So, as you can see, the 10 gallon aquarium is not holding 10 gallons of water. A fancy goldfish, which the Oranda is, has to be in a tank no smaller than 20 gallons. It looks like he might have injured himself by running into something in the tank. If you keep him in that tank, you will stunt his growth. The skeletal parts of his body will stop growing, but all of his internal organs will continue to grow. This will cut his life span very short, and cause him to die slowly and painfully. If you want to help him, I would get him a 20 gallon tank with a filter for a 30 gallon tank. Make sure you run the new aquarium through the 6 week cycle period before you put him in. Goldfish are huge waste producers so you need to do a 30% water change every other day as long as he is in the small tank. You can keep him in that tank while the new one is cycling, but make sure you are changing 30% of the water every other day. Keep an eye on the bump and if it gets worse, you can add a little aquarium salt to his tank until it is healed. The ratio is 1 teaspoon of dissolved aquarium salt to 5 gallons of water. Salt does not evaporate, so when he is healed, you will have to remove the salt from his water. You do this by doing a 50% water change one day and then 50% again. Wait a few days and remove 25% of the water. Make sure you are replacing all the water with clean conditioned water. If after all this, he is not better, or he gets worse, let me know.