Molly & Goldfish

[fish-o-fish]

Okay so I have a 70L tropical tank, a 21L coldwater tank and a 15L hospital tank... today I decided to move my Calico goldfish from my 21L into warmer waters (the 70L tropical tank), but my large male molly has been chasing him around attacking him ever since. So I am in the process of separating them and putting the calico goldfish back in the 21L tank.

I've been trying to do some research, but can't seem to find a clear answer. Are male mollys and goldfish severely incompatible?
What about a male molly and 2 comets? He seems to be leaving those 2 alone.. just attacking the large pretty calico goldfish.

Any insight would be much appreciated. I'm relatively new to fish-keeping.

Thanks.

EDIT: Ok, now with the Calico goldfish out, the male molly is attacking the comets. Should I remove them too before there's a fatality?

 

[micko]

Do you have any female mollys? They should take his mind off the rest. Not sure if they compatible with your others but I definately wouldn't be putting any coldwater fish in with tropicals.

 

[KittyKat]

Mollies and comets (common goldfish) are not compatible due to different temperature requirements.

Common goldfish should have at least a 6*2*2 ft fish tank to grow to their full adult size. Pond will also do.

Fancy goldfish are not compatible with common goldfish because of difference in ability to swim, etc, so the commons can abuse the fancies and out-compete them for food very easily.

Fancy goldfish should have at least a 4*2*2 ft fish tank to grow to their full adult size, preferably a 6*2*2 ft.

Mollies may be compatible with fancy goldfish, but not in a 70 litre tank, which is too small for both species. Mollies should have at least a 3*1*1 ft tank.

 

[Athena]

Yes, I agree with that above. Not a good idea to be putting coldwater fish in with tropicals and the tank is too small for those coldwater fish you have. If you can't get a larger tank for them, maybe consider rehoming them and setting up the small tank for something else. Just an idea.