Requesting info about rescue goldfish

[Miss Bad Wolf]

I'm trying to write a novel where the MC (Main Character) has a rescue goldfish (a moor).  I was thinking of having her get the fish at a pet store, but remembered that there are the fish who need to be rescued and the people who rescue the fish.

I'm trying to research how it might work for the MC and the fish.

I'm not sure how this process work.  I'm toying with the idea that the moor's previous caretaker kept the fish in a bowl or other tank too small for an adult goldfish.

I'm thinking of one of the housemates of the MC somehow find out about the poor fish.  She has a marine tank but knew the MC has a lone goldfish, so she rescued the fish and offered the MC to take care of the fish.  With both of them working together, the fish started to feel better due to their care and having real swimming space.

My questions are how would being in a bowl for a few months (at most) affect the fish's health?  Can the young fish still grow bigger if rescued in time and put in a better environment?

 

Any other info do I need to know for my story and fictional moor.

The moor is sort of based on my moor but different back story and different gender.  I think the real fish is a boy but I want the fiction fish to be a girl.

Also what causes tumors in moors?  I'm thinking of giving the fictional fish a tumor as I think moors tend to get them.

[hannah]

Goldfish can and do compensate for stunted growth. A few months in a bowl won’t have much effect on the size of the fish but poor water quality may cause the fish to have a lowered immune system and be in generally poor health. A stunted fish will usually continue to grow when moved to ideal condition. Stunting can also delay sexual maturity in fish. 

Tumours can be caused by many things but most likely genetic predisposition. 

Hope this helps!