Corydora loss

Question
I have a 2 corydora, both pandas, and all of the sudden one day one of my corydora, Jack started acting really wierd. It was going up and down the tank and then I checked bak at about 30 min and it started swirling around the top of the tank with its belly 3 times its normal size sucking in air. I came bak 3 minutes later and it wa dead! My poor corydora..Is there anyway you could possibly help me out?

Answer
Good evening Donald, thank you for your question.

I am really sorry to hear about your panda cory. There are varying reports about this cory - some say they are hardy, others say they are sensitive. In my opinion, they are among the most sensitive cories in terms of water quality.

Cories can take in air from the surface directly, and will do so once in a great while. If you are seeing them making a run to the top often for air, this is an indicator that there is ammonia or nitrite presence or, absent these, a high presence of nitrates. What you need to do now is test your water with a test kit, to see if this was the cause.

Ammonia and nitrite must be at 0 ppm always, and although nitrates at a level of up to 20 ppm are acceptable, do your best to keep nitrates at 10 ppm or below for this species. Although cories relish meaty foods such as shrimp pellets (Sinking Carnivore Pellets by Hikari are a fave of my cories) they seem really happy with the presence of live plants, if only because they love rooting around in a fine subtrate. So if you really want to make your cories happy in the future, even if your tank is not a planted one, try adding a live plant in a pot with a fine subtrate such as aquatic soil. The plant will absorb nitrates (a natural fertilizer) and your cories will love the sandy substrate.

Tankmates should be peaceful, and don't forget that cories love to shoal. They are most comfortable with six or more of their kind, so try to incorporate at least three into your tank - but not until you have your water tested and changed out, especially if it is less than ideal. I would perform a 25% water change just in case, with dechlorinated tap water.

Make sure your cories eat enough, as they are too often left with only the dregs of the communal feeding. Frozen bloodworms are a real treat, you can try target feeding with a turkey baster in their direction if you feel your cories are not getting enough to eat. New Life Sprectrum sinking pellets are small in size but so nutritious, all my cories really do enjoy eating these particular leftovers!

Add an airstone to your tank if there is not a powerhead or other bubbler to break the surface tension of the water. Power filters do this to some extent, but it never hurts to add more circulation. Test your water, making necessary adjustments with partial water changes as needed. Add another couple of pandas or other cories (most will shoal with any other corydoras) - and see if this regimen doesn't help your other one to live a long and healthy life.  

Also, do take a look at these sites' profiles:
http://www.scotcat.com/factsheets/corydoras_panda.htm
http://www.planetcatfish.com/catelog/species.php?species_id=267
http://fish.mongabay.com/species/Corydoras_panda.html

The first is the longest, the third is the most concise. Reading about our pets really helps us understand them!

Good luck, Donald, feel free to write again anytime.
Nicole