I know that you are not supposed to mix the two, different water preferences, but I did anyway. And I would like to report that the two (a red male crowntail and a rosey red goldfish) are doing perfectly fine. Niether care that the other is there. I also have 15+ guppies and 3 (2 died, need to replace) neon tetras. As well as 2 apple snails that think their tanks (goldfish doesn't like them). Has anyone else had this happen? And PLEASE no bashing!
This is NOT a good idea, it does not matter that they get along now the fact is that goldfish and betta should not live together ans there is a reason for it. Goldfish as Olypia said will eat betta. Getting along now means nothing. A snake in a zoo located in Germany lived with a mouse for three months before it killed and ate the mouse. It didn't mean mice and snakes can live together it only means you have a ticking time bomb in a tank and it sounds like your tank is also WAY overstocked which in itself isn't good either. Please get the betta his own tank with a heater since betta's need 78-80+ temps. Even a small 2.5 hell 1gallon would be better for your betta.
Not to mention the stress of different water temps could cause some of your fish to become ill...
Goldfish are bad tanks mates also, because they basically harass or eat anything they can fit in their mouths. They may be fine now,, but when the goldfish gets bigger it will surely nip your betta and/or eat it.
the tank is a 30 gallons tall tank. They are Rosey red goldfish (also called Rosey Red Feeders) the grow up to 3inches long. the do look like minnows. The tank temperature remains at 76*F and i was told that both Betta and the Rosey Reds can happily live at that temp. The Betta is also extremely calm from what i have seen in the past. I thank you for the advice, it will be considered!!!
I found the rosey red minnows, Olympia t appears that you are right and that i need to have a talk with Walmart about false advertising and see how many fish i can get! Can "rosey red minnows" remain with the betta???