If you are unaware of what a betta is, They are fishes that belong to a special group called labyrinth.  What this basically means is that they have a special organ that allows them to take in air directly from the surface.  Something that other fishes can't.  The most important thing to do for you weekenders, is to leave the container open to oxygen. 

 

You should request the follow things from the person.

CASH$$$  (justkdding)

Net,

water conditioner,

betta food.

You can get by for about a week with those items. 

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For short term care(1-3 days) you wont need to change the water generally. Remember not to keep the betta in direct sunlight or by a window.  Before you go out in the morning, or after you eat, give the betta about 1-2 pellets.  Before you go to bed, give the fish another pellet.  You dont ever want to over feed your betta fish, or do anything to surprise the fish.  Just feed the fish about twice a day will limit your chances of messing up. 

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For longer care(7-14 days) You may be required to change the water 1 to 2 times.  Thats when the net is needed. See how i change my water and at the bottom of that page i tell you how to change the bettas water.  The feeding is the same as short term, about twice aday.  There isnt much care that is needed.