What is up with this corys tail?

[lmhicks101]

This is a cory that was hatched in this tank. It’s about 4-5 months old. None of the others in its batch have the crescent tail. Some days it struggles with buoyancy and other days it’s fine. It’s tail is closed up right now but usually is open and gorgeous. 

[nabokovfan87]

A lot of schultzei black have poor genetics due to a lot of inbreeding and lower availability.  These might be a different species, but if it's schultzei then I would consider trying to add more from another source.  It looks like a deformity to me.

Normal Tail:

Edited July 30, 2023 by nabokovfan87

[Lennie]

If I'm not wrong, sometimes in bettas, the fin curls may happen due to genetics and/or long term hard water exposure. What's your water like?

@Odd Duck do you have any idea Duck?

[lmhicks101]

On 7/30/2023 at 5:01 AM, nabokovfan87 said:

A lot of schultzei black have poor genetics due to a lot of inbreeding and lower availability.  These might be a different species, but if it's schultzei then I would consider trying to add more from another source.  It looks like a deformity to me.

Normal Tail:

The parents are emeralds and albinos I got from Petco. 
 

@Lennie the waters usually 6.8 ph, 2kh, 8 gh

 

[Odd Duck]

@lmhicks101 Just to be clear, that’s not an emerald cory.  There is lots of confusion between Corydoras aeneus AKA green cory or bronze cory (which is what yours appears to be) and Corydoras splendens (previous name Brochis splendens) which is known by the common name of emerald cory.  The easiest way for me to tell is to count dorsal fin rays - C. aeneus has 10 or less (usually 8-9) and C. splendens has more than 10 (usually 11-12).  C. splendens also has a very slightly longer, straighter face than C. aeneus and get slightly bigger on average.

The majority (but not all) of the albino cories in the trade are a color morph of C. aeneus (green/bronze cory) and would of course be able to breed with normal color bronzes since they are the same species.  C. splendens cannot cross breed with most albino cories (but could breed with an albino form of the same species).  There are albinos of other species and it is incredibly difficult to know what species you have without any markings.

I agree with @nabokovfan87 and @Lennie, I think this is likely a deformity that could be related to genetic issues and inbreeding.  It could also be a completely random deformity.  I would recommend trying to bring some fresh genetics into the group via normal color bronzes, not albinos as they are more likely to have other recessive genes that could potentially lead to deformities.

[lmhicks101]

@Odd Duck in all honesty, these weren’t meant for breeding. I got 5 of what I thought was emeralds and 3 albinos. The parents are no where near the colors of the offspring. They’re almost albino their selves with light shades of green but all the babies are that color. I’ll probably go to a LFS and grab a male and female to add to the genetics.  

[lmhicks101]

@Odd Duck here’s another from its clutch as well as the albinos. Yeah they’re all C. aeneus. 

Edited July 31, 2023 by lmhicks101

[Odd Duck]

C. aeneus can be quite variable depending on their substrate color.  Darker substrate triggers much darker colors, lighter substrate will show the much lighter body colors.  I’m not sure how it’s happened but I have zero good pics of my bronze adults.  Loads of baby pics, but diddly squat for good adult pics.  😆 The lights went off 2 hours ago (before I got off work) or I would take one.  I did include a juvie pic on light substrate and a back end shot of a couple going after whiteworms.  🤷🏻‍♀️