Goldfish not growing

[kamalei.86]

I have a goldfish that is not growing as fast as the others. I have a 55 gallon tank that has been running for about 1 year and a half now. It has 2 aquaclear 70s and a sponge filter. About 10 months back I bought two telescope butterflies from buygoldfishonline from their stock selection . One from the red and white stock and the other from the black and red stock. The one from the black and red stock is growing considerably faster than the white and red. Recently the white and red has been having issues i.e,: resting at the surface near the filter, slower movement during feeding time, and tends to just float with the current of the filter.
I change 25- 50% of the water every week and feed appropriately. Every other fish in the tank is flourishing except for that fish.
I'm out of ideas with what is Wrong with the fish. Could it just be that it was in poor conditions from the seller and has stunted growth? Has anyone else had problems with ordering from them? She is the cutest runt ever but if there is nothing I can do for her I would feel bad to keep letting her live on like this.

 

[nirbhao]

What are your water parameters? How many other fish are in the tank?

 

[Kishore]

Maybe it is his nature??

 

[kamalei.86]

What are your water parameters? How many other fish are in the tank?

Ph: 8
Nh3: 0ppm
No2: 0ppm
N03: 20-30ppm
I have 4 goldfish in my 55 gallon

 

[Coursair]

Pic of your tank ?

Goldfish need room to grow.

What is your complete stock ? Are they all Fancy type GF ?

What are you feeding ?

Check SolidGold on YouTube for some great GF care vids.

People growing out GF do big water changes. 90-100% changes for some of the show quality fish.

I think SG uses 75g for 3 Fancy Goldfish ?

They do a majority of their growth the first year. There is discussion that major frequent water changes clear out the growth inhibitors.
http://www.about-goldfish.com/The_Goldfish_Gazette-July-2017.html

 

[kamalei.86]

I have 3 telescope butterflies and a entail in a 55 gallon. For some reason I can't post a pic. Another thing I heard is that you have to find a balance between proper filtration but not producing too much outflow for fancies because they are crappy swimmers? Lol. She is the littlest guy in the tank so maybe I have too much overflow. Today I found her stuck on the filter vent. I'm thinking about doing a quarantine tank with just my sponge filter from the tank so she can rest. Any ideas on reducing my outflow?

 

[kamalei.86]

Btw thanks for the article link. That was some good info. See I'm wondering if she had stunted growth due to the seller. I bought the fish from their red and white stock so it's possible they held a bunch of them in one tank.

 

[Coursair]

I'd QT her. Fancies often have issues.

Make sure to only use use sinking food

 

[kamalei.86]

She didn't make it. Even after quarantine I dissected her and found out she had an enlarged swim bladder. And her organs were bigger than her body mass. Because she never grew I'm thinking it was genetic or from previous tank conditions. Sad day.... I'm making sure to reduce overflow on my filters. 7 years in the hobby and there's still something new to learn