For 3 Comets that size, I wouldn't consider anything less than a 55, with a lot of filtration and 50% water changes weekly.

For a 55 with Goldies, for a lot of bang for the buck, it would be hard to beat an Emperor 400. If you keep the flywheel clean, it really will turn over the water in a 55 every 15 minutes. I like them especially not just for the bio-wheels, but also because if you buy a pair of extra baskets, you can also buy a roll of bulk filter fabric, cut it to fit, and hold it to the top part of a basket with rubber bands, then just fill the other full (top & bottom) basket with charcoal and amonia chips, and with a total of near 24" of carp, you will use it up quickly, so there too, buy it in bulk.

With Goldies living indoors at room temp., you will need a lot of filter media changes, so the cost of 2 additional baskets results in quick pay back over buying premade refills.

Your other option would be to buy a deep rubbermaid watering trough at least 125 gal. size, put it in a dark, cold place, add an air stone to keep the surface from freezing over, and let the fish go dormant for winter. Many Goldie and/or Koi keepers with shallow ponds winter their fish in that manner, but to do it, you must take them into a state of semi-hibrination over the course of several weeks, cutting back on the food, then withholding it completely over winter.

I'll be wintering 10 Waikin in a 300 gal. trough in the barn in just that manner. If you want a more detailed explanation of dormant state overwintering, ask some of the Koi folk on the Pond forum.

Or, keep them in the house and play with them. If they aren't hand tame pets now, by spring, they will be.

BTW: If you decide on keeping them indoors, do NOT pay pet store prices. Check out-

http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+3579+14448&pcatid=14448

Then- at the bottom of the list, the extra media baskets-

http://www.drsfostersmith.com/product/prod_display.cfm?c=3578+9998+3626&pcatid=3626

birdwidow,

Thank you for all the information! I am printing this out to give to my DH. Thanks again...

Adichristi:

You are very welcome. If you and your DH do decide to keep them in the house, a great source for tanks is eBay. I've scored more than a few large tanks for a pittance of what they sold new that way and even if it's a leaker, as long as the glass is good, they are simple to reseal.

In fact, if someone lists a leaker, it will likely go really cheap and all it takes to get it back to brand new watertightness is a tube of 100% silicone sold at any home center, a caulking gun, and some blue tape.

Good luck, and enjoy your Comets. I keep many different species of tropicals, and as lovely as they are to look at, I really have the most fun, playing with my Goldies.

birdwidow, How much gravel should I put in the tank?

Adichristi:

Unless you are planning to keep live plants in a Goldie tank, you don't need any gravel, but if you want it for appearance, you would be best off using not gravel, but smallish rocks; small enough to not look out of place in an aquarium, but too large to get caught up in a 1" siphon tube.

You can buy nice looking rocks, usually called medium river stone, at most large home centers. Just enough to cover the bottom would do. They are mostly rounded, but do pick out and discard any that have sharp edges. Large graden centers that carry landscaping stone usually have a nice selection of fancy stones and for what you need in most any aquarium, the cost would be minimal and it's amazing how pretty the fancy colored river rock can be, when it's wet.

Goldies are beautiful and can be charming pets, but they are also filthy. They can't help it. One 7 inch Goldie bulks the equvilant of several hundred Guppies, so tank cleaning, especially getting out the mulm trapped under the stones is very important, and why I suggest the river stone. You can easily move them around with the siphon to suck out every speck of mulm, but not have any stones get into and stuck in the hose.

If you want to keep live plants in with them, a good choice is java fern. I have some large JF tied to a rootwood log in my Goldie tank and they leave it alone. It also seems to do better in the cooler water of a Goldie tank than it does in the heated tropical tanks.

Give them a very strong air stone too. Cold water fish need far more oxygen in their water than warm water tropicals. My Goldies like to play in the bubbles. But Wakin don't make as nice looking a fish in an aquarium as do Comets. It's that weird body shape. Beautiful viewed from above, but oddly mis-shapen in appearance from the side.