PlanetCatfish.com

These cute little guys were in a tank with corydoras paleatus and corydoras arcuatus (that's the one with the racing stripes nose to tail, right?) and all were being sold as "Peppered Corys". There was a tank labeled corydoras julii that had identical fish to these pictured, so I thought that is what I was getting. Now after studying the Cat-eLog I'm not so sure. My best guess is corydoras sodalis. What say you good people? On an unrelated note, the last six corydoras I've purchased I've paid a total of 7$!

From the Cat-eLog............

Probably the most misidentified fish commonly found in aquatic retailers who incorrectly sell it as C. julii.

Wow! That is exactly it! Thanks. You deserve a cookie.

I wonder if Petco would give me another free fish if I tell them their error.

I thought the identification section of the C. julii was pretty clear - it even LINKS to the C. trilineatus:

Often you will see fish for sale as Corydoras julii but they are actually

Corydoras trilineatus

. So, if you bought as fish as julii, it's almost certainly C. trilineatus from the upper Amazon. The real C. julii will turn up from time to time as although it originates from the upper Parnaiba system in the lower Amazon drainage, it is found in the Rio Para where commercial fish collectors operate.

--
Mats

Real Corydoras julii only come from Corydoras specialists and even the tank/farm raised C. trilineatus continue to be misidentified. Many old texts are still in wide use and help to perpetuate this identification error.
Besides, Petco has many old labels to use up.
You have discovered that the lack of sophistication of the large fish and pet stores can work in your favor when it comes to finding cheap but rare catfish which would be much more expensive at a shop that knows it's fish.