Most of the common ones have been said. I've had six goldfish in a 6G (gallon per fish!), no cycling, emptying out and scrubbing, then refilling, being lazy when feeding and not sticking my fingers in the pot, promptly throwing half the food in. The airpipe thing happens quite often...hmmm....but I've installed the one-way things now.
The worst thing I've done is with the Python. I had it sucking and it started coming off the tap. I didn't stop it sucking and ran out to stop the tap...my favourite fish got sucked in, an oranda goldfish, and pretty badly ripped up. I had to perform fishy surgery...but he is alive and well now. And I don't even leave it near the top of my tank when I'm out the room.
I also forgot to put the lid on my frog tank after a WC and two of them mysteriously disappeared...I have yet to find them, but my room is getting recarpeted in September so I will have to then, I suppose.
My most sickening mistake was not finding out how much this all cost before I got into it...
The worst thing I've done is with the Python. I had it sucking and it started coming off the tap. I didn't stop it sucking and ran out to stop the tap...my favourite fish got sucked in, an oranda goldfish, and pretty badly ripped up. I had to perform fishy surgery...but he is alive and well now. And I don't even leave it near the top of my tank when I'm out the room.
I also forgot to put the lid on my frog tank after a WC and two of them mysteriously disappeared...I have yet to find them, but my room is getting recarpeted in September so I will have to then, I suppose.
My most sickening mistake was not finding out how much this all cost before I got into it...