You're going about it all wrong. What a n00b. Bacon bits is just going to fatten him up. Plus you're training him wrong. Just listen to the professional kid.
1. Diet. You need to get him on a diet that will build lean muscle. Simplest way to do that is to fill a glass with muscle milk and place your goldfish in it for about 45 seconds. As he becomes stronger, you will be able to keep him in there longer, but if he dies the first time you put him in for 45 seconds, it was weak of heart. This is a great way of weeding out a weak fish right from the get-go. Make sure that you allow the milk to become room temperature. No more, no less, to help him simulate the transition from his warm tank to the cold toilet water.
2. Training. To begin training, plug a sink and fill it up. Then place a metal screen over the drain and put the fish in while it's still full. Goldfish aren't the smartest creatures. That is the main obstacle to overcome. By using a metal screen, when the drain sucks up the last of the water, your fish will get dragged across the metal screen if he doesn't fight against the flow and manage to flop away from the drain near the end. This teaches them quickly to swim furiously against flows of water. Again, if your fish is weak of heart, this will weed it out. That screen fucks their shit up. Do this at least 30 to 40 times over a period of a couple weeks to get him in shape while adding in proper diet.
3. Final steps. If your fish has made it this far, it is a fighter. It has developed a look in his eye that shows he is a warrior. He's battle scarred, and he's seen combat and conquered. Now, it is time for his final test. Your fish isn't a balanced fighter. He knows one scenario. The sink. As I said, it's not a smart creature, but it has become dedicated. You must make it understand that at any time it can be called upon to fight for its life. To do this, we bring in hell week. Hell week will break your fish down to nothing and bring it back up higher than you ever thought possible.
During hell week, you will wake the fish at 0430 every morning. Place a screen over the sink and turn on both nozzles full blast. Leave him there for an hour, and as the days go by, increase the amount of time he stays in there. As soon as he has completed this task, he can have chow. Take him straight from the sink and place him into a glass of muscle milk. He should be able to survive for 2 minutes at a time in there now. After his two minutes, place him back into his hell week barracks: a cereal bowl which must be placed in a PITCH BLACK space so the fish can't see anything. Also, find an audio track of baby goldfish screaming in pain over being anally raped and play it over and over where your fish can hear it. If you can't find a track, ask these guys to make you one.
At 1800, roughly 12 hours later, you put him in the toilet. The second he hits the toilet bowl use a wooden spoon to stir the bowl. Don't spin it so that he has absolutely no control and is just bashing around the walls. The point of the exercise is to have him be very close to outswimming your whirlpool, but barely not being able to. Once you get bored of doing this, place him in a glass of muscle milk again for 30 seconds (don't give him time to eat a full meal.) Leave him there until 0430 the next morning. Any time you wake up to piss though or something like that during the night, slam a spoon up against the side of his bowl a few times to fuck with his head some more. Continue this process for exactly 1 week.
At the end of this week, if your fish has survived, he is a champion. He has a strong will to live, and will surely prevail in his task. Give him two weeks to recover, and see how strong your fish now looks. After two weeks, he is ready.
4. Day of warm-up. Do some basic sink exercises to get him back into the groove of things for a day or two before you attempt the flush. On the day of, place him in a glass of water and put the glass in the toilet so that when you flush the toilet, the water in the glass won't be affected. You just want him to see the power of the toilet. Flush it a few times. He knows the toilet from hell week. It will remind him of the one task he couldn't overcome. He will be determined. Place him in the toilet. He will swim around aggressively. He is in the best shape of his life. All of his training has come down to this moment and he knows it. IT'S TIME.
5. Flush him down the toilet.
