I also enjoy raising native cats (mostly flatheads and bullheads found in
central Oklahoma) in my tanks. They're fine when small but once they get to
an inch or so the other fish need to watch out. I think you did the right
thing by going to a cat-only tank, because there are lots of other reasons
that cats and tropicals don't mix. Tropicals are warm water fish and cats do
better in cool water. Tropicals like a bit of salt in the water (I know this
is a contentious issue but I do it) and cats can't tolerate much salt, if
any. With this in mind I usually run four kinds of tank:

Heated, with salt - tropicals (mostly bettas, guppies, and swordtails)
Heated, no salt - tropical cats like corys and plecos, and sometimes snails
Not heated, with salt - goldfish
Not heated, no salt - native cats and other native fish

All of the native cats I've had are nocturnal (or get that way after they
are older) and hide during the day so they're not much fun to watch. I
usually give them a rock pile or brick pile and they are quite content to
stay in there until lights out. However they must be terrifying night
stalkers, considering on how my tank populations (especially guppy fry)
would be reduced by the next morning back when I kept native cats and
tropicals together. They will eat literally anything and I give them
everything from tropical flakes to leftovers from dinner to commercial
catfish meal. They are seldom tame enough to come out and eat when I feed
them but the food all disappears and they do get bigger. They tend to stay
together and as long as one isn't a LOT smaller than the others they
probably won't prey on each other, but I do have one vanish without a trace
every now and then. Commercial cat food and dog food often has chemical
additives that I wouldn't want in a tank, but a twenty-pound bag of catfish
meal from the local feed store is only a few dollars and will last forever.
My goldfish like it too, but there's another fish that will eat pretty much
anything you throw into the tank.

--
John Goulden


About four or five months ago I collected four very small (less than an
inch) baby catfish from a local pond and put them in a planted ten
gallon tank I had sitting around. After researching a bit about them I
figured out they were brown bullhead cats and will get about a foot
long in the wild - smaller than I expected but still fairly large.

So after they got big enough to not be harrassed by my cichlids (and
they had been in my tanks long enough for me to be confident they
weren't carrying anything nasty) I threw them into my big tank. They
had great fun and doubled in size in no time. Then their mouths got
bigger than some of their tank mates...

They ate all of my guppies (no big loss there, I was going to donate
them to the petshop anyway) then my last remaining tiger barb that
hadn't been eaten by the severums, then two african dwarf frogs,
several snails etc. I traded all of the remaining cichilds to the LFS
for store credit and turned my big tank into a catfish only tank.

So now I'm wondering just how far the "they eat anything" phrase might
go. I'm used to doing lots of water changes after owning a host of
destructive cichlids that were plant intolerant so I overfeed a lot so
they'll grow fast. Anyway I was looking at them today and wondering if
they can eat stuff like catfood (like friskies for instance) that I can
buy in bulk for a tenth of the price of fish food. I already know
they'll eat every kind of fish food that exists, any kind of creature
that will fit in their mouth, chicken, tuna, and earthworms.

I've noticed these guys are far more hardy than just about anything I
could buy in the petstore, and I suspect that if I don't find some bulk
amounts of food and start overfeeding soon then the biggest cat is
going to turn on his sibblings and I will have one very large cat
instead of four.

Thoughts?
-Daniel