"muddyfox" wrote in
ups.com:

Hi,

I've had some Cory's for about 12 months now. They were sold to me as
Corydoras julii but as they've grown their markings have come to look
more like the reticulated form. Anyhow, I have recently been in the
process of upgrading one of my tanks and the two corys have been
temporarily housed in a 30 litre betta tank with my female betta and
two amano shrimp. Since moving them I've noticed that they have this
shimmering green iridescent sheen particularly around the gill covers
and on their flanks just behind their heads. The sheen extends in
increasingly tiny patches down to the tail and it quite beautiful.
However, under some light it looks golden which is what's causing me
to worry as I've read that Velvet can appear as tiny golden salt and
pepper spots. I've been keeping fish for a number of years and have
never had a case of velvet so I'm not really sure exactly what it
looks like.

I think your fish has definitely been mis-identified. I'd guess that
they're corydoras paleatus, and that the coloration means you're taking
fantastically good care of them...

Another pic of c. paleatus similar to yours;

http://www.moje-akvarium.net/pic/ryb...aleatus-01.jpg

species summary at Fishbase

http://fishbase.org/Summary/speciesSummary.php?ID=10926
&genusname=Corydoras&speciesname=paleatus

What you have is definitely not c. julii...

My tank conditions are as follows:

Ammonia 0 ppm
Nitrite 0 ppm
Nitrate between 10 and 25 ppm (tap water is 20 around here)
Ph 7.6
Temp 79 F


c. paleatus like things a little on the cooler side, 74-78 F, but I
wouldn't bother to change things. Just don't go any higher on
temperature. What you have now is a reasonable compromise for the cats
and the betta. Other than that, you've got some great parameters,
there...

I'm thinking that this might just be their natural colours, perhaps
showing more now they are in a smaller tank and easier to observe but
I wondered what you all think - I don't want to miss it if it is a
problem.


Yeah, the smaller tank is probably putting the light source closer to
the corys, which is why you're seeing it more. I have a trio of c.
paleatus in a 20g planted, and only get to enjoy the iridescence when
they make a rare sortie into the upper 1/2 of the tank. They're a
great aquarium fish...

Regards
DaveZ
Atom Weaver