What to do with my fish?

Question
Over the holidays, I am going on vacation, and will be gone for 8 days. I have 5 goldfish, and they are in a filtered tank and the fish are very healthy. There are live plants in the tank as well. I plan on putting a feeder block in the tank. If the block dissolves too quick, I want to know how long goldfish can survive without being fed? I have a son, and I don't want to arrive for him to see his watery friends dead. I also don't want to spend my vacation worrying about my fish's health. There is no one that is able to take care of my fish during my vacation unfortunately because they are all away. The pet stores nearest to us do not offer a pet sitting session either.

Answer
Amanda,
I am not a fan of feeder blocks for exactly that reason. The rate at which they dissolve is unpredictable!  A goldfish can go approximately 6-7 days without food. That is the least of your concerns however. Goldfish are huge  waste producers! They don't have a stomach therefore everything they eat comes out as waste, which in turn becomes ammonia, then nitrites. Nitrites are deadly!! One goldfish requires a minimum 20 gallons of water, and each additional goldfish requires at least 10 gallons each! In your case, your 5 goldfish should be in a 60 gallon tank. You will not be home for 8 days and there will be no water changes. The best thing you can do is make sure you do a water change before you go. Usually it is 25% but I am thinking 50% would be better. Do this right before you leave. Set the feeder for every other day. Do not use the block. They are very unpredictable. Get the feeders that are programmable. If your fish are in a tank smaller than 60 gallons, I guarantee there will be problems. If you do the water change the day you leave and get a better feeder you will have a better chance of having live fish when you get back. Good luck.