Lethargic Fantail Goldfish please help!

[watermelonmango]

Hello, I have a 26.2 gallon tank with 7 small common goldfish and 1 fantail goldfish, each about 1-2 inches long including the tail. Yes, this is probably overcrowded so I will try to upgrade the tank soon. I have had the fantail for 2.5 years and the commons for 1-2 years. They're always fed tetra flakes, twice a day.

Since yesterday, the fantail has been lethargic and lying at the bottom corner of the tank, breathing rapidly. It would swim around with the other fishes, then rest at the bottom occasionally.

This morning, it was lying at the bottom for what seemed like a long time, and the other fishes started picking at it so I transferred it to a yellow tub by itself.

Now it's laying on the bottom of the tub, breathing rapidly, and its fins are limp. It also has a faint black streak on part of its tail but not sure if that is just part of its coloring. Sometimes it swims to a different part of the tub, which has no filter.

Why is it sick? Unfortunately I don't have any water tests to test the ammonia or nitrate levels, but I did a 40-50% water change in the original tank yesterday. I tried feeding it cooked peas in case of constipation but the fantail didn't eat very much of it.

 

[Mcor]

Hello, I have a 26.2 gallon tank with 7 small common goldfish and 1 fantail goldfish, each about 1-2 inches long including the tail. Yes, this is probably overcrowded so I will try to upgrade the tank soon.

Since yesterday, the fantail has been lethargic and lying at the bottom corner of the tank, breathing rapidly. It would swim around with the other fishes, then rest at the bottom occasionally.

This morning, it was lying at the bottom for what seemed like a long time, and the other fishes started picking at it so I transferred it to a yellow tub by itself.

Now it's laying on the bottom of the tub, breathing rapidly, and its fins are limp. It also has a faint black streak on part of its tail but not sure if that is just part of its coloring. Sometimes it swims to a different part of the tub, which has no filter.

Why is it sick? Unfortunately I don't have any water tests to test the ammonia or nitrate levels, but I did a 40-50% water change in the original tank yesterday. I tried feeding it cooked peas in case of constipation but the fantail didn't eat very much of it.

Hi!
We need a little more information. How long has the tank been set up? Are you able to take a sample of your water to your LFS for testing? You need to get a liquid test kit (API master test kit) ASAP.

Unfortunately, you are very overstocked, in fact, your fantail alone stocks the tank. The common goldfish require a huge amount of space as they can grow huge and are much more suited to ponds.

 

[watermelonmango]

I set up the tank 2 1/2 years ago, so the fantail is one of the first fish I got. I will try to test a sample of my water soon...
What should I do in the meantime? Should I return it back to the tank?

 

[jlk]

Lots and lots of big wcs with temperature matched, properly conditioned water. The black areas are ammonia burns and the conditions in your tank are likely very toxic. As already mentioned, you need a liquid test kit for ammonia, nitrite, nitrate and ph. The API fw master test kit is suggested. I would also recommend rehoming the commons to happy pond environment. Please ask if you have questions!