What fish to get??

Question
Hello-
I setup a 20 gallon aquarium just over a month ago and I believe the tank has just finished the cycling process :).  I have 3 zebra danios, 2 female mollies, and one neon tetra (4 originally) that survived the first month.  I do a 25-30% water change about every 2 weeks and all the levels (ammonia, nitrite, nitrate) are good now :).  So I am ready to add more fish.  Any recommendations?  I like hardy fish (no neon tetras) that don't require expert maintenance.  I was thinking of getting a couple gouramis and maybe some black tetras.  Any ideas on which fish I should get and how many I should add at a time?

Thanks!!

Answer
Hi Julian!

Well, I could answer your question best if you write back and let me know what kind of water you have. Is it soft, or hard? Or more specifically, what is the pH, hardness, and alkalinity, if you have those parameters.

The reason I ask, is that it is soooo much easier to keep fish that are adapted to your water chemistry. Neon tetras really don't do so well in hard water. They are, as you've observed, not very hardy anyhow. But soft water, especially water that is low in alkalinity, has some concerns...it's really quite a bit easier to keep fish in hard water, actually. Here's an article that discusses this topic:
http://www.wetwebmedia.com/FWSubWebIndex/fwhardness.htm

The common dwarf gouramis that are suitable for your sized tank aren't very hardy, I'm afraid, since many gouramis are prone to Dwarf Gourami Disease. This causes lack of appetite, disorientation...and most strikingly, ulcerations, and almost always leads to certain death. The larger gouramis such as three spots, blue or gold gouramis, pearl or moonlight gouramis, are not affected but grow too large for a 20 gallon. You would do fine with Colisa fasciata:
http://images.google.com/images?svnum=10&um=1&hl=en&q=colisa+fasciata&btnG=Searc...
Which is known as the "giant gourami", since it seems that it's Colisa lalia that is the affected kind.

The black tetras you mention would be fine! They adapt well to hard water, even if their environment is soft water originally - they've been tank bred for generations. They are also one of the hardier tetras. X-ray tetras and red-eye tetras are similarly hardy. All tetras like to school, so unless you plan on keeping at least three, nix tetras.

What about barbs? I am very fond of gold barbs:
http://freshaquarium.about.com/cs/cyprinids2/p/goldbarb.htm
http://www.aquahobby.com/gallery/e_sachsi.php
Rosies are another favorite, though they get big...

I would also recommend, of any livebearers, platies - since they seem less "touchy" then swordtails, or especially, mollies. Livebearers need hard water to be healthy, though, since in soft water they'll be very delicate, prone to things like fungus and finrot and overall will not thrive.

Do you want fish that hang out at the top, bottom, or middle? This is another thing to consider! Corydoras make lovely bottom dwellers, they love being in groups, so get at least four of them. Zebra danios are top dwellers are super active, so that's probably enough activity at the top...

Ok, well, I hope I gave you something to think about! Here's an article on hardy first fish: http://www.bestfish.com/tips/061898.html
I agree with their choices, though again, some get a little large, like the blue gouramis for example.

Take care! Feel free to write back.
Nicole