Geez Elgin, you scared me when I saw the title of this thread!
I figured it had something to do with that Jay H 237 character here on CD!*
Well, anyways, the tank I have now is a 10 gallon. I still have a 5 gallon in the attic but I upgraded to the 10 about 2 years ago. I'm running a filter, an under gravel filter, and heater with it. The heater is neccesary since I have tropical fish and I keep the tank at 76-78 degrees at all times. This is a freshwater tank.
Now with a small bowl and a goldfish you don't need all this. With normal room tempature the goldfish won't require a heater, plus a heater won't fit in most bowls. I used to have goldfish with a small bowl and I changed the water when it started looking cloudy. This was about every two weeks in the winter and about every week in the summer. I didn't run any filters with the bowl. As for the cat, the above suggestions of screen sounds good. I never had a cat so I never had this problem. Whatever you do don't put solid plastic or anything else to block the top of the tank, the fish do need air. Feed it two to three times a day only. A little "pinch" of food is all it will need. The only other thing I would use in the tank is "Chlor Out" or some other treatment to neutralize Chlorine and Chloramines if you're filling the tank/bowl with tap or well water. For a small bowl 3 or 4 drops and for a tank like mine about 40. If you're only changing part of the water change the drop ratio accordingly. It only costs a few dollars a bottle and it lasts awhile.
*Just because I filmed my fish tank to test my new digital camera with film mode doesn't mean I don't have anything better to do!
Now excuse me, I think I'll go look at Ebay and see if there's a life I could bid on.
