A couple weeks ago, I asked Tish, my ex-college roommate and resident goldfish expert, some questions about my comets' fishtank. Here's her (expurgated) response:
Hey you,
{snip}
For the filter: When you change the water, I am not sure if you're just dipping a bowl in or...?, but whatever container has the dirty water that you are taking out of the fish tank to dump - before you dump the water take the filter out, put it in the dirty water container, and rub your hands on each side RUBBA RUBBA RUBBA to get the major gunk out. You can also then upend all of the water in the filter into the dirty water container, and then when you put the new water in, also add some to the filter (so that both sides of the filter box fill up, otherwise the impeller won't run correctly. You'll know if you do it wrong because it will try and try and try to suck the water up and it will go HNGAHNGAHNGA but once you have enough water in the filter box it will suck the water up and quiet down).
Some people only feed their fish once a week. For your guys one small pinch (small! Think cumin-sized pinch not garlic sized pinch. Or if you like cumin, substitute in something you don't like, anise or some such. Anyways) every other day will do 'em fine. I know. Our guys are consummate beggars too. Matt's been forbidden from feeding them ever now because he would give them "treats" every time he walked by, and then wonder why the water was so dirty and smelled like Lake Erie.
{snip}
Love,
Tish
Yeah, I really do have the bestest friends.
I didn't know you had comets!
My fish beg too. the nice folks at the fish store I go to also say that you only need to feed them every three days or so...but who can resist those winsome begging mouths? I don't have goldfish, but all tropical fish do that.
Who can blame them? Who wants to be fed every other day??