Name: Corydoras pygmaeus
Origin: Rio Madeira (Brazil)
I LOVE Cories! And Pygmy's are one of my favorites. They are great little fish, the perfect little bottom dweller. These are great for smaller tanks (big ones too) because their small size doesn't strain the bio load very much. Just as attractive and hardy as their larger cousins.
These fish are great for small tanks. They grow to only 2 cm and will eat anything. They are like full sized Corys in every way: they like to school, constantly scour the bottom of the tank for food, are very active, take gulps of air from the surface of the tank occasionally, "blink" their eyes, easy to feed, etc. The only difference is that these guys are TINY! Very peaceful, sweet, and adorable! Keep them with smaller, peaceful fish and you'll have a great tank!
My success with this delightful species has been as follows: I keep them in an intimate (70 liter) tank with my adult and baby Balloon Mollies, a few Guppies, a small Clown Pleco and some Glass Shrimp. I have six of them in this set up and they are great little schooling scavengers who enjoy taking on a smallish blackworm whenever they can. They like to rest on a small piece of African driftwood. I keep a little salt in the tank and the temp at 27°C for the Mollies and their babies. These little guys are hearty little fish in this setting, but they need an environment scaled down to their size to feel secure in. I think a sandy bottom helps their success as well. I watch this little gang as much as any other of my tanks. Also, their price won't set you back a young fortune!
I have a school of 7 right now in a 75 liter long tank with sand bottom. At first, I tried to put them in a 450 liter tank that was over 60 cm deep. In there they stayed on barely submersed plants (risking being eaten by my african butterfly fish. Yet in the shallow 75 L they stay on the bottom. Would agree that they do indeed get stressed in deep water. Also, I have mine with some Otocinclus and they sometimes school together.
I am amazed at these little fella's. I have a group of five. They are surrounded by fish 10x their size, but they don't even seem to notice. All day they're working, working, in the gravel and decorations. I've even seen them resting right on the back of my 15 cm Pleco. They are wonderful for bottom cleaning and very entertaining!
These lovely little fish have been a great addition to my 80 litre tank. I bought them on a whim to bulk out an online order of fish, and I am glad I did! I have three just now and have now ordered four more. They like to school together (which is something I was looking for, but didn't find in other so called schooling fish) and quite often gang about in the middle of the tank as well as along the bottom, with occasional forays to the surface for a gulp of air. They just get on with their own business and don't bother any other tankmates, in true corydoras fashion. They are very hardy in my soft water, pH 6.5, temp 26°C tank too. I had a bad bout of Ich recently that killed off my blue and gold rams and sparkling gouramies - but these little guys (and my pandas) just grooved right on through 30°C temps (for two weeks) then 2 teaspoons of salt per gallon (for two weeks).
They aren't flashy showstoppers like blue rams, for instance - no one is going to stop at your tank and go 'Wow!' at seeing them, but I find my attention turning to them, to watch their antics as they busy away cleaning up food leftovers, etc, just as often as any other fish in my aquarium.
They are tiny, but a school of them would look good in any tank, I'm sure. And their strain on your bioload in your tank would be minimal, if you got some. A great (and inexpensive) purchase for any tank in my opinion - if you come across them.