Does Tank size effect Bluegills and Goldfish living in the same tank?

[Ocean Railroader]

I was woundering I once had two Bluegills who had raised from when they where less then a half a inch long and had them trained to eat fish food. I also had five Goldfish all long with them living in a 75 gallon tank at one time. The Bluegill would seem to go into the tank and pick out a spot to take as his own and not let any other fish get near it. While the Goldfish would swim around the tank and randomly bottom feed. Sometimes the Bluegill would go after the Goldfish and sometimes he didn't really care and would swim around the tank sometimes with the rest of the fish. The Bluegills where very well fed so they where not really hungery in wanting to eat the Goldfish which where double their size.

But as the Goldfish and Bluegills started to get bigger and bigger they the Bluegills became more agressive.

If a group of two Bluegills and five Goldfish where taken out of a 75 gallon and moved into a larger 300 gallon tank or 1500 gallon and up wards would the Bluegill and goldfish change their behavoirs to one another such as that the distances in the tank would prevent them from running into one another. Or that the Bluegill would be able to pick out a large space of his own and have more space to stay there and the Goldfish would be able to go to the other side of the tank out of his sight?

 

[Rays of Sunshine]

There are 3 behaviors that I have seen, read, or heard regarding bluegills and other tank mates:

1. The bluegill is docile until one day it changes it's mind (I think the fish was provoked or maybe a temperature increase triggers breeding behavior)

2. The bluegill is the dominant fish in the tank. It will patrol the entire tank and correct any fish that it perceives as challenger or needs to be reminded to stay in line.

3. There is not enough room and territories, so the bluegill will fight for the best spots.

One thing I believe everyone agrees, that bluegills are naturally aggressive.

As far as goldfish and bluegills are concerned, bluegills will always dominate. Maybe a common goldfish may be the best choice since it is the fastest swimmer and doesn't have long fins. I think it would be best to keep the fish in separate tanks.