At this point we decided that Bufford and The Golden Retriever shouldn't be replaced immediately. We needed to figure out what we needed to do differently. Upon closer inspection, we realized that the filter/pump wasn't working quite like we had thought it would, and that we perhaps needed some more oxygen in the water. So we bought an air stone volcano thing and waited.
Phineas made it for a full week. Conner took good care of him, feeding him at the right times and even reading a few books to him.And Phineas didn't just make it - he survived Josiah's eager help on several occasions. One morning Joey fed Phineas 2-3 weeks worth of food at once. And another day he found the net and was trying his hardest to catch him. And then we realized that the filter that is supposed to last several weeks, was already full (thanks to, I'm sure, three dead fish and a massive over-feeding) and not functioning properly.
So yesterday we decided to completely clean out the tank, fill it with fresh water, and get Phineas a couple of friends. We had added the little drops that take the chlorine out. And while Bret and Conner were at the pet store getting new fish, Joey proudly came to me with the empty bottle of drops. "I give Phineas some mo watah!" Yup. He had dumped the whole bottle into the tank.
Phineas had made it through so much. There was no way I was going to let him go now. Luckily, we had already been preparing to clean the tank out, and had some chlorine drop-treated, room temperature water sitting there ready to go. So I grabbed the net, fished him out, and dumped him in one of the pitchers of water.
And he made it! Bret finished cleaning the tank, added the new fish - Candace, a red platty and Perry, and little suckerfish catfish thing, both named for more characters from Phineas and Ferb - we put everything away where Joey can't get it (we think, anyway!), and they all made it through the night!