Blue Fish

Blue Fish
What is that blue stuff in betta fish containers?

You know how when you go to the pet store and then there's those shelves with the betta fish in those little plastic containers? Now I'm just wondering, why is their water bluish and what is the purpose of the blue stuff?
I'm planning on getting a betta fish tank eventually. Should I own this substance and if so, what do I do with it? And another thing: I wanted to have bamboo plants in the tank, so will the blue stuff harm the bamboo?

The 'blue stuff' is a mild dose of malachite green http://en.wikipedia.org/wiki/Malachite_green that prevents external fungus and parasites on the fish. In pet stores and during shipping, they often medicate all of the stock instead of individually inspecting and treating sick specimens. When you have hundreds and hundreds of fish, it's a smart way to keep as many alive during transport as you can.

If you're planning on getting a betta fish tank, then you don't necessarily need to buy medications like malachite green unless your fish gets sick. It's better to dash to the pet store at the first sign of illness than it is to stock medications on your shelf waiting for your fish to get sick. If you stock medications buy them before the fish gets sick, then the meds may reach the end of their shelf life and expire before the fish ever needs it.
There are some things you will need to buy if you plan on keeping a betta. A heater will keep the water at 80 degrees Fahrenheit, which is necessary for the betta to stay healthy and keep a strong immune system. Colder temperatures lower bettas' immune systems because bettas come from Thailand in the wild and never experience cold in their natural habitat. The smallest heater is really for a 5 to 10 gallon tank, so that's really your minimum tank size.
A filter makes your life easier, and is also a good investment. By filtering the water, the fish lives in cleaner water and stays healthier longer. Beneficial bacteria lives on the surfaces in the filter. One gram of activated carbon has a surface area roughly equivalent to a tennis court, so that's a lot of room for the beneficial bacteria to live on. A filter, with many grams of activated carbon, therefore has a ton of surface area and is a great help to adding beneficial bacteria to your tank. Here is more information about why you want a filter and what it means to have a 'cycled' tank: http://www.fishkeeping.co.uk/articles_51/fishless-cycling-article.htm

Malachite green does not harm plants or invertebrates, but any copper containing medication like Copper Safe (R) does and will destroy your live plants such as bamboo. Usually medications say on the package whether or not it will kill plants.