Discolored Cardinal

[graemesmith]

I just got a batch of 10 cardinals and popped them into isolation for a few days to check them out before introduction to the main tank.

All happy and swimming well.

But one is discolored - solid black in the root of the tail and the root of the dorsal fin. Seems just as happy as the rest, not deformed, not gasping, swims fine - just a funny color - like the ugly duckling really.

The color is almost like a solid pigmentation in the structure of the fish - not a black spot on the surface.

LFS said - (I paraphrase):

Sorry about that we will swop him for you
We seem to get quite a few like that
We can never sell because people don't trust them and we "dispose" of them
We don't know either.

Well - I didn't take him back. He seems just OK and healthy as the rest but he IS still in (lonely) isolation till I can figure.

Any ideas out there?

TIA

 

[Alien Anna]

Cardinals show their condition by their colour. He may have been injured in transport, he may be elderly, he may (for some reason) be more shocked by the pH hike than the others (cardinals are wild-caught in pH 5). I'd suggest you keep an eye on him. LFS's do lose a large number of any particular shipment of cardinals.

 

[graemesmith]

Well - he is now happily back with his bretheren and seems none the worse

 

[graemesmith]

I made some other inquiries - here is an answer I recived from staff at the Steinhart Aquarium of the California Academy of Sciences

Greetings,

Your question to Dr Eschmeyer about black pigmentation at the tail and fin bases of your tetras has reached me. It is, of course, almost impossible to make a diagnosis from afar, but as your fish are acting normally I might be tempted to suggest melanoma of some kind. Many small fish are subject to melanoma and indeed some are used in research (swordtails etc.) because of this propensity.

I think the only ways you can solve the problem (especially with regard to marketing the animals) is to get a diagnosis. A pathology department in a vet university might do this for free, or alternatively take one fish to a vet and ask for tissues to be sent out for analysis. That will cost a few pennies. At least you would then know if this is indeed natural pigmentation or something more sinister.

Good luck