I had Yellow labs, dwarf puffers, chines algea eaters and convics in with my pond (600 gal) fish/koi/comets/goldfish

I never kept track to see how many were eaten the non pond fish are just fish caught during tank cleaning and put in the bluebox pond for the summer.
I have grates I can put in one end for the smaller fish to hide in.

 

I have a large koi that I'm wondering would thrive in a heated Cichlid tank or not. He would be the largest fish in there.

 

I kept cichlids and koi before. It will just depend on which cichlid species, the size of the tank, ammount of oxegen and filtration as koi being keep in warm water grows fast, eats more. They required more oxygen as well or you gonna end up with a dead koi with flared gill from not getting enough oxegen. Also large ammount of water changes as well or your cichlid will suffer from hole in the head disease. Also make sure that the kois dont outcompete the cichlids for food.

 

so long as you keep it well fed
Koi like most fish will eat anything that it can get in its mouth

 

Strikes me as probaby being a bad idea. Koi aren't really what I'd call tank fish to begin with. Then the temperature ranges for cichlids and koi aren't really compatible either. Finally you could potentially have agression issues depending on the cichlids involved.

I mean, you might be able to swing it temporarily; but it's probably not going to be ideal in the long term. It's that kind of thing that always comes back to bite you later.

 

I would think that PH would be a concern if your putting it in a African cichlid tank.

 

I have them outside pond that’s 12x13x3.5

 

It can probably be done but conditions wouldn't be ideal for at least one of the species and you've got to have a MASSIVE tank like King-el probably does or a pond like mike.

 

Yes, I have successfully kept 2 blue African chiclid, 3 Showa koi and two aquatic turtles, and a 12 inch plecko ALL THE TIME that uuįall together, in harmony