I was just wondering what size pond (gallons) is needed to keep one.

If it's fully grown then I say at least 200 gallons.

you'll need more than that,
this is an article by CFC about tank size, and gives you the ratios of space that the fish need: http://www.fishforums.net/content/Other-Catfish/116411/http-www-fishforums-net-index-php-showtopic-116411/

A red cat could get to 5 feet (I think they get to 6)

http://animal-world.com/encyclo/fresh/catfish/redtailcat.php

Something like a 7 long x 4 wide x 3 high would last the catfish a fair while. However a 12 x 6 x 3 would be ideal for most red tails for life.
Joel

This post has been edited by -=Joel=-: Jul 14 2006, 09:34 PM

In another topic about these fish CFC says:

Thanks for the replies

Peopel have seen 6 feet RTC in the wild and there are unconfirmed locals reporting sitings of 7+ feet.

They are an active fish that tend to spend a fair amoutn of time finding food to eat. Really you want to plan for a fairyl large fish. 5 feet long is seen in captivity, so at 4x2x1.5 body length you would want 20x10x7.5 as an ideal size.

If you have more width you could possibly sacrifice length. I would be more than happy with a 17x12x7 pond. Remember though, that on top of this you would need some serious filtration such as a huge wet/dry sump or massive fluidised sand bed.

The advantage to a pond that size is that if you go mad with filtration you should fit two or three RTC in there (and it does appear that they will shoal).

As for the food bill of feeding them servings of whole trout twice a week...

a fully grown one will need atleast 1000gs to be happy at 6ft, to be happy but you could keep one alone in a 16x6x6 tank.