What constitutes aggressive in goldfish? i just put 2, 2" goldfish, in a new 10 gal tank. One of them ive had a while with 2 other goldfish. they all got along, no problems. the 2 others died March 21. (long story). I got my remaining goldfish a bigger tank and today i bought another goldfish, and moved them both to the new tank, by a long acclimation process that lasted all day. when they were finally both in the tank, the original gold fish started bumping up against the new one and sort of crowding it. the new one acted like it didnt have the strength to swim even though it was very active and fast in the pet store. will the bullying behavior of my first fish abate?