Endler fry dying one by one

[TooManySnakes]

First a picture of this gorgeous endler line which I am lucky enough to have in my possession. I purchased these fish in the beginning of February from a breeder about 100 miles south of me. After driving to pick them up, I quarantined them for one month. I treated once with kanaplex as one fish developed a fin infection but otherwise had no issues.

They have since been in a 29 gallon tank with some least killifish. The adults have been doing well and get a varied diet. A female dropped their first clutch about 2.5 weeks ago. I counted 10 surviving fry 24 hours later. They have been growing quickly due to heavy brine shrimp feedings. However, I am now down to 4 fry. 

I frequently observe the fry in the open water without being harassed so I don’t believe the issue is fry predation. I’ve seen two fish develop consistent symptoms which makes me believe the issue is disease. Their body shape distorts, they have trouble swimming, they spend most of their time near the surface, they appear to lose proper buoyancy and always swim with their head above their tail. By the time, I notice these symptoms they quickly perish. This disease is not yet effecting the thriving population of least killifish in the tank.

Just hoping someone has run into this before and can give me some guidance. Thank you!

 

Edited April 26, 2021 by TooManySnakes
Formatting

[CalmedByFish]

Following. I recently had an adult endler male develop a similar body shape to the fry in the bottom picture, and he died a couple days later. 

[Kirsten]

Oh man, that's so sad! I don't have a definitive answer, but I've been raising practically hundreds of endlers for months now and I haven't noticed anything like that. My feeling is it might be something genetic, especially for a rare colorway that's probably pretty inbred at this point. You might want to try breeding the male(s) out to some generic endler females (I'd recommend in a separate tank) to see if the problem's with him or one of the females. Fingers crossed it was just a bad first (or last) brood from a female.

Otherwise, sounds like you're trying to give them the best! I'd also recommend a few more floating plants to hide under and around to help reduce some stress.

[Eric R]

I don't have a lot of experience with Endlers personally, but my first thought was the same as @Kirsten, if the adults all seem fine and the rest of the tankmates seem fine, I'd tend to think that inbreeding could likely be the cause, especially if you're seeing signs of deformities. I also agree with Kirsten's suggestion of trying to breed genetic variation back into the line. @WhitecloudDynasty has several threads documenting his practices for breeding new lines, and he posts a lot about how he introduces diversity by breeding back into the line and then continuing to select for the same traits, so I'd recommend reading over some of his threads for ideas on good breeding practices (unfortunately, not all breeders practice good practices).

Edited April 27, 2021 by ererer

[CorydorasEthan]

I agree with @Kirsten and @ererer. It's probably a genetic problem due to interbreeding.

[TooManySnakes]

Thank you everyone for your input! I sincerely appreciate it. At the end of the day doing a little outcrossing sounds a lot easier than dealing with some nefarious pathogen 🙂