Runts

[Hellfishguy]

A while back I had a large spawn of wild Apistogramma cacatuoides. After eventually rehoming the larger specimens I discovered about a dozen much smaller individuals remaining in the grow-out tank. Since then they've grown somewhat & have begun to produce fry, although at over a year old they're still undersized.. Will they ever reach full size, & if not, will their fry?

 

[yukondog]

Every batch I have of apisto's, kribs or angles, I get runts, I cull the ones that dont make it and move on. As far as if they will produce young of normal size I have no idea.

 

[Samala]

Chiming in to commiserate: I also see a small percentage of runts in nearly every batch of cichlids I've raised.

The only time I don't see these seems to be if I allow fry to grow up in the main display rather than a grow out environment. Likely that any 'runts' in that environment simply don't make it and I don't see them expire because it is so heavily planted.

That said, I'm always looking for new methods to improve my approach. Heavy feeding with enormous daily water changes seems to help, but I like to think all the fish in my care should be able to reach their genetic potential.

I'm considering putting a batch of fry into a much larger outdoor growout this spring/summer to see if that improves growth rate with ready access to daphnia, mosquito larvae, and other things I don't usually culture.

Super curious to hear if anyone has seen normal sized offspring from runts. Surely in F1s from wild type the genetic basis for size is still there.

 

[Mike Wise]

IMHO runts occur because they are out-competed for food by more eager/aggressive siblings. I get runts,, too. About the only way to avoid this problem is to periodically separate smaller fish from larger, and raise them in a separate tank. Then do it again and again and again ... .

 

[Bowluvr]

A while back I had a large spawn of wild Apistogramma cacatuoides. After eventually rehoming the larger specimens I discovered about a dozen much smaller individuals remaining in the grow-out tank. Since then they've grown somewhat & have begun to produce fry, although at over a year old they're still undersized.. Will they ever reach full size, & if not, will their fry?

With good care, at least most their fry should reach normal size. They may or may not reach it.

 

[Samala]

IMHO runts occur because they are out-competed for food by more eager/aggressive siblings. I get runts,, too. About the only way to avoid this problem is to periodically separate smaller fish from larger, and raise them in a separate tank. Then do it again and again and again ... .

How have I not thought of this???

I put four of my "runts" into their own growout last Friday based on this advice and they already look a bit bigger than the three "runts" of the same age I left in the main growout.

Thanks Mike!

 

[Andy452]

IMHO runts occur because they are out-competed for food by more eager/aggressive siblings. I get runts,, too. About the only way to avoid this problem is to periodically separate smaller fish from larger, and raise them in a separate tank. Then do it again and again and again ... .

Yep I have also done this too, but then you hit a limit on how many tanks you have! But separating 2 or 3 times is very helpful

 

[Hellfishguy]

Update: One of my runts has developed a unique coloration (the burgundy patches). He’s fathered many young and my hope is they’ll reach full size and inherit his appearance.

 

[Apistomaster]

IMHO runts occur because they are out-competed for food by more eager/aggressive siblings. I get runts,, too. About the only way to avoid this problem is to periodically separate smaller fish from larger, and raise them in a separate tank. Then do it again and again and again ... .

This practice will also help achieve more balanced sex ratios.