C. trilineatus color morph, or trilineatus X agassizii hybrid?

[bekateen]

Hi All,

I have a batch of

Corydoras trilineatus

juvies, about 1-2 months old. Most of them look normal, but at least one (and maybe two) is particularly dark, and looks more blotchy than the others in coloration (photo: Left: "normal" looking trilineatus just starting to show its lines; Right: dark blotchy sibling).

The parent tank has 5 adult trilineatus that spawn regularly, and five adult

Corydoras agassizii

which have never spawned in the 1+ year since I got them, and which I've never observed engaging in spawning-like behavior with each other or with the trilineatus. That said, it is true that the two species like to swim together in one big group, along with the lone

C141

that I have in the same tank.

The cats are still pretty young, and as I mentioned the normal looking fish are just starting to show their lateral stripes. The dark blotchy cat is from the same batch of eggs but is a little larger than the rest of the baby trilineatus. Is this simply an unusual color morph or mutation of trilineatus, or is this a the result of an agassizii sticking his "you-know-what" where it doesn't belong when the trilineatus were spawning?

I mentioned that there may be a second dark fish in the clutch - that fish is the runt of the litter, and I still feel like it's too small for me to tell with confidence whether it's going to get darker, although it does look a little dark already. If in the end I have only one fish with the dark blotchy color, I will feel ambivalent about deciding the issue of color mutant vs. hybrid. But if the smallest cat also darkens up, i.e., if I get two cats with this dark blotchy look, I'm more inclined to suspect a hybridization event because the odds of two eggs in the same batch (of about 10 eggs) having the same mutation would seem to be very low.

Has anyone ever heard of a trilineatus X agassizii hybrid before? I look forward to your feedback.

Cheers, Eric

[bekateen]

Here are some more photos. Hopefully these are a little better. As to the dark cat's coloration, I'm also noticing that its pectoral fins (esp. the pectoral ray) are very dark compared to the normal trilineatus.

[Karsten S.]

Hello Eric,

interesting, C. trilineatus definitely are quite variable. I had one specimen (offspring) without this lateral stripe on one side.
Up to now I think both options (hybrid or "oddball") are possible.
But I guess in a few weeks we should be able to tell...

Cheers,

[bekateen]

Thanks Karsten. Believe me, I'm as eager as can be to see how this fish (and the other melanized "runt" in this group of juveniles) matures. I'll keep you all posted with further photos when the fish get closer to adult size. And if it does turn out to be a hybrid, what I'd like more than anything is for the guilty C. agassizii to STOP messing around with my trilineatus and START messing around with my other agassizii! LOL
Cheers, Eric

[bekateen]

Hi All,

It's been almost three months since my last post to this thread. Here is my follow-up, showing you how these siblings developed. I got five fry out of the original eggs. One died, but the remaining four have been growing well. As you can see, they appear to be perfectly typical trilineatus. No hint of agassizii in them, so I'm confident hybridization didn't occur.

The only difference I see in the coloration among these siblings, as a reflection of the dark pigmentation shown in the earlier photos of two of the juveniles, is more or less of the black vertical bands on the lateral plates above the mid-lateral horizontal black line. Individuals # 1 and 2 have bolder vertical lines than individuals # 3 and 4.

Looking back at the parents, I've got three males, one with many bold vertical black stripes on the upper body, and the other two males with fewer and weaker vertical stripes. I suspect that more than one male "got in on the action" with the mother during courtship and mating.

Cheers, Eric

[christiansen]

good job with the update Eric !

[bekateen]

Thanks, Christiansen.

I just traded them in at my LFS yesterday, so there won't be any further photo updates. I hope they find a good home and have a long life. (same thing I want for my own kids, when they move out! )

[christiansen]

no need for another update , the fry turn out to be C.Trilineatus . You did a good job raising them , now let's hope they find a good home !