Bettas and corydoras-help please!

Question
Hi Christy I'm Lily!You see I have a betta (Ripple) and he lives in a 10 gallon tank, and I'd like 3 Corydoras!BUT I HAVE NO FILTER!!Do they absolutely need one?Is there anything I should be careful about when adding them?I mean I've had two bettas and with that so much reasearching them, you wouldnt beleive it, I know everything I think I should about them but not too much about Corydoras!I'm only 12 and I adore my betta and I'd love another addittion too my tank like corydoras!I'd love for you to please answer my questions
                               -Thankyou ,lily

Answer
Hey Lily
Sorry, but yes they should be in a filtered tank.  Really the only fish I can think of that would do fine without a filter, is a betta or gourami(labrynth fish).  I'm sure you know, they get their oxygen from the surface, where as other fish take it in through their gills in the water.  The filter helps agitate the water surface, which allows gas exchanges-CO2 and O2 to take place.  

Now, before you say can I just add an air stone then? :)  For the price of an air pump, the tubing, and air stone, you can pick up a filter for a 10-20 gallon tank for the same price.  If you're in the US, Walmart sells an ok brand of filter for I think $10-15.00 for that size tank.  A filter is good also, to help clean the tank.  

I love cory cats, they're one of my top 3 favorites :)  You've done some research on them, you know they prefer groups of at least 3 :)  And, they should be the same kind of cory cats also-all albino, all emerald, etc.  I used to have a bunch of them, I think I had 12 at one time.  I've had most of them about 6-7 years, down to only 3 now.  And, one of them laid eggs a few weeks ago, I scraped off the eggs and put them in a breeder net, but only 1 fish ended up surviving.  It's about 1/2 inch now, and absolutely adorable lol.  I'm hoping they'll breed again so I won't have to buy anymore.  

I strongly suggest only getting them if you can get a filter, and if you do, I think 3 would be good for your size tank.  There's also a variety called a dwarf or pygmy cory cat.  I believe they only grow to about an inch or so.  If you can find those, you could probably get away with getting about 5 of them.  They should get along fine with the betta, betta's hang out at the top mostly and the cory cat at the bottom.  I can't think of any fish I've had that's ever messed with my cory cats.  If you do get them, just make sure your tank is fully cycled, and no ammonia or nitrites are present in the tank, and your nitrate level is under 20 ppm.  And just adjust them slowly to your water by adding a little bit of water to their bag while it's floating in the tank.  Take at least a good 30-45 minutes to let them adjust.  That's really all I can think of.  Here's a link that explain cycling a fish tank and ammonia, nitrites, and nitrates.  

http://freshaquarium.about.com/od/startupcycle/Step_5_The_Cycle.htm

Here's a few sites with info on cory cats as well.  The first one, you'll have to scroll down and look for the ones you want, has several listed on there:

http://www.fishprofiles.com/profiles/list.aspx?category=1

http://www.badmanstropicalfish.com/profiles/profile18.html

http://www.badmanstropicalfish.com/profiles/profile78.html

Hope that helps, and hope you can get the filter!!  Let me know if you have more questions!

Christy