Aggressive goldfish

[Phoenixphire55]

I recently got a new, larger tank to move my fish into. These include a 3 inch goldfish and some corys and several mollies. I got a new goldfish today and since my quarantine tank shattered mysteriously (clean-up was ****...), I put the new goldfish in the tank with the other fish. My old goldfish and my new one are both fantails, and I hoped they'd be friends, but the old/slightly larger goldfish has been chasing around the new one quite a bit and trying to nip it's tail. Is it possible for goldfish to kill each other? What should I do if this continues? Is this likely to continue forever or will the old goldfish probably get used to his new friend and stop attacking it?

 

[Zagz]

Goldfish are not usually aggressive. What size tank is it, is it the 30 gal? I can't give you an honest answer as I have never seen aggressive goldfish.

The mollies and the cories should not be in the same tank as the goldies. They are warm water and the goldies are cold water fish.

 

[jsoong]

Fantails are not usually aggressive, but I suppose there will be exceptions. What you are seeing may just be them sorting out their pecking order. Give them a day or two & see if things settle down <or you may have to reutrn one if things get out of hand>.

A second possibility is if your old fantail is a male & you put a female in the tank. During mating season, the male will chase the females relentlessly. They will bump into her backside (not fin nipping tho) and there are reports that the bumping is so rough that the females will lose scales & the odd one can get bumped out of a tank! <So keep the lid on.>

And yes, you have to be very careful when mixing golds with other fish .... your choices in that 30 gal is not really optimum. A goldie purist would keep species only tank.

 

[Phoenixphire55]

I know my goldfish shouldn't be in the same tank with the others, but I'm one of those people who made the mistake of getting the fish before learning about it. The first fish was a goldfish, and then I just got mollies after that because I wanted non-aggressive fish. Do goldfish and mollies both do ok at room temperature? If not what is best for each?
It'd be cool if one was male and one was female, but I think the bigger one is biting the other one's tail. My only options are leaving it in there, or moving it to a 15 gallon ACF tank, or giving the goldfish its own 5 gallon tank (barf).




:-|

 

[Phoenixphire55]

I'm pleased to say that the goldfish is no longer harassing the other goldfish and they appear to be friends now