What fish are good to put in the same tank as goldfish? What about bettas? Will they attack the goldfish?

For goldfish, I recommend a plecostomus,a snail, a frog, or other goldfish. If you are setting it up as a coldwater tank, DON"T add tropical fish. As for the bettas, you could try adding JUST 1 but keep a close eye on your fish for signs of aggression (such as torn fins exe.) Neons would just be a tasty snack as your goldfish will grow pretty quickly in a 10 gal. Here, this site might help you, http://www.kokosgoldfish.com/comfish.html

Fancy goldfish need at least 10 gallons each minimum so even with your new tank only 1 goldfish will fit in it. If you would like more fish I would suggest getting a 29 or 30 gallon. That way you can get a friend for your goldfish and add maybe a bristlenose pleco or a snail. Don't get a common pleco they like to suck on the slime of a goldfish and will eventually kill it, also don't get a tropical fish like neons or guppies. Goldfish are coldwater fish and have completely different requirements then tropicals. Goldfish get really big too and will eat the small tropicals as soon as they can fit in their mouth. Betta are also a bad idea, they not only are tropicals as well but most don't like having any company and will attack and kill them. With the right care a goldfish can live over 20 years and atleast 8 inches long, depending on the type they can get even bigger. Have fun with your new goldie friend and if you ever need any help check out http://www.kokosgoldfish.com/ it has a great forum with lots of friendly people.

Bettas attack almost all species of fish except very big fish. All other fish are good to put with goldfish except the ones that attack because goldfish are very calm fish and don't like to be disturbed.

ONLY GOLDFISH CAN GO WITH GOLDFISH. Even then the rule for baby-juvenile fat fancy goldfish is 10 gallons PER fish. For longbodied goldfish such as comets/commons/shubunkins, they need a minimum of 20 gallons PER baby-juvenile fish. For adults, they will need atleast 40 gallons per goldfish since all goldfish get 12-14 inches. Goldfish excrete too much waste to be housed with tropicals. Also goldfish require cooler waters since they have primitive gills and require a high amount of dissolved oxygen in the water. Tropical fish such as bettas, mollies, platys, neon tetras, ect.. need warmer water and will not be able to handle the amount of waste goldfish excrete. For those of you who have tropicals mixed with your goldfish, there is a major difference between just surviving, and actually thriving and i can guarantee that your fish are just merely surviving. Why the hell cant people research before they get pets???

any fish really!

Bettas are attack fish, they will kill anything in the tank with them.

Bettas are japanese fighting fish, you shouldn't even put two of those together, they will kill each other! As for goldfish, try the neon fish, they seem to get along well.

It is not good to mix tropicals with goldfish. Black Moores are a type of goldfish and will do well. Goldfish create excessive ammonia and it';s not good for tropicals. And a betta willattack any other fish, especiallyones with long fins. Bettas do best in small bowls, singly.

I have a male betta (one!) in with my two upside down catfish and they get along fine together. So a betta may be fine with the goldfish too. I think they'd really only attack other aggressive fish.