Keeping Goldfish/Koi in Ponds?

1) Both can survive outdoors through the summer and winter. Which is better? Personal choice. When fully grown, koi will be much larger. They are the fish you typically see in an ornamental pond. If you get goldfish, stick w/ comets, and not oriental/fantails as they are slower and more apt to be eaten by wildlife.

2) To combat heat in the summer, having surface water plants, ie water lilies, hyacinths, water lettuce, will shade the pond, keeping it cooler and helping to control algae. In the winter, you will need to find out how deep the frost line is in your part of the country. In the midwest, its 36" so the deepest part of my pond is 42". This helps to ensure your pond does not freeze into a solid block of ice. You will need to use a pond heater or trough heater to keep a hole in the ice so that it allows for gas exchange.

5) The pond will cycle as would an aquarium, but your typical pond is much larger than an aquarium. This gives you more room for error. Most people initially do not overstock the pond in the first month, as koi and comets tend to be more expensive, and cycling happens at a slow, natural rate.

6) I recommend using a rubber pond liner for the base and the walls. Dig a hole, throw it down, double stack of bricks/pavers on the top and your done. The liner I bought was from Tetra. The pond is 15 yrs old, and no problems w/ liner cracking.

7) Yes, but you will need to make sure there wasn't any chemicals, etc on them. Same w/ a fish tank.

8) Any fish is going to do better in a pond. The larger body of water will dilute toxins better, more room to swim for larger fish. All aquarium fish originated from the wild and almost all lived in large bodies of water.

9) There are many pond filters and designs to choose from, submersible, external, pool filters, etc. This is going to come down to personal preference and budget. You may find that you will make your own filter from pvc and parts from the hardware store. Regardless of the filter the one piece of equipment which I wouldn't go w/out is a UV sterilizer. This will kill the free floating green algae which makes ponds look like pea soup.

Tetra makes a lot of pond products and I would look into what they have to offer as far as building and designing a pond. Plan it well b/c it's hard to change once you've started.

Koi pretty much take over the pond as far as fish go. Try adding frogs. Look for whatever is local. The Koi will eat the young but will not hurt the adults (unless they are really small) and it will add an interesting mix that you can't get with adding other fish.