Unintentional mini-platies: why the size difference?

[PineSong]

@GoofyGarra's recent post about platies not breeding (linked below) reminded me of this situation I'm curious about.

Nearly two years ago I gave my coworker some of my juvenile male platies and guppies for a new tank he was setting up at the office. Summer 2022 I have him some male swordtails for it as well.

I feed his fish when he's away and I've noticed his platies never grew. They are well fed with high quality foods, have direct sunlight as well as LEDs and lots of plants. The guppies and swordtail all reached normal size. The platies have remained miniature. Unlike dwarf platies, they are normally proportioned or actually a bit slender--no chunky torso.

Due to office renovations, I am currently boarding his tank at my house so I seized the opportunity to photograph 2 of his males with my last remaining male, Bacon, who is either their father or their brother.

I'm not sure what would cause this size difference. All my females are normal chubby platy ladies of typical size, and most of them must be these guys' sisters.  Here are photos of Bacon and just two of the miniature fellas.

 

[Guppysnail]

Could there be a temperature difference between your original tank and the office tank? That may account for smaller growth. 

[PineSong]

On 2/16/2024 at 7:20 PM, Guppysnail said:

Could there be a temperature difference between your original tank and the office tank? That may account for smaller growth. 

I suppose there could be, but his tank does have a heater on it and I probably set it to 78 when the tank was being set up, which is where I keep mine. Also, would the swordtail get full size if the water was so cold it kept platies miniature? 

[Guppysnail]

On 2/16/2024 at 7:30 PM, PineSong said:

I suppose there could be, but his tank does have a heater on it and I probably set it to 78 when the tank was being set up, which is where I keep mine. Also, would the swordtail get full size if the water was so cold it kept platies miniature? 

I doubt it.  I just know some fish stay smaller at lower temps so was throwing it out to help you brainstorm a why. 

[Scapexghost]

You should try breeding them out. Id buy some mini-platies

[mtnmonster]

I've experienced this with my platys. I have a female that looks normal but is only maybe 1¼ inches and all the rest are 2½ to 3. She also is a loner. She really don't hang around the others, but other than size seems to be healthy. She was the only one I kept out of her siblings because she was so small and I thought she wouldn't make it. She almost 2 now.

[jwcarlson]

This has happened with my discus and it's been hexamita once and worms a couple of times.  It's usually whack a mole, maybe lowest 1 or 2 in the pecking order are stressed enough that the worms get to them.  Treatment usually brings them around and they start growing even.

Different species, obviously, but one of them looks like white pooping?  But that could be a fin.

[GoofyGarra]

@PineSong have these mini-platies been dropping fry?

 

[PineSong]

On 2/17/2024 at 6:54 PM, GoofyGarra said:

@PineSong have these mini-platies been dropping fry?

 

They are all male, so no. I only gave my coworker male fish as he did not want to deal with population increases. I kept females from the same batches of fry, and I sold a bunch. The ones I kept are full size for females who have never been bred. They aren't as big as mom platies who have bred a lot, but they are a fraction smaller, not 50% smaller. 

I discontinued breeding my platies because the blue ones I was trying to breed more of appear to have the black cancer gene and many of them died from tumors before they were 2 years old. I only have one male and about six females left, and they live separately to prevent breeding. 

[GoofyGarra]

@PineSongdid you ever figure it out? Sounds like my friend is having a similar situation where the females are significantly growing but the male isnt.

[PineSong]

On 3/28/2024 at 4:37 PM, GoofyGarra said:

@PineSongdid you ever figure it out? Sounds like my friend is having a similar situation where the females are significantly growing but the male isnt.

Nope. The little males are still the same size. They now live with my normal sized male platy, a male swordtail that I bred (also normal sized) and male guppies in my 20g long kitchen tank and they have not changed a bit. They appear healthy and normal other than size.

[Huckleberry]

It can be the genetics. I've had super small swordtails and very large swordtails from the same batch. So I would select breed the large ones and keep the small ones in another tank with out females. Sometimes a couple would grow large but the others would just stay small. 

[knee]

This is really interesting. Maybe this is how the dwarf red coral platy started? Are you planning to breed them? 

My swordtail gave birth this weekend and i was able to separate 25+ fry. Will try to grow those out and keep the smallest male and female. 

[PineSong]

On 4/8/2024 at 3:48 PM, knee said:

This is really interesting. Maybe this is how the dwarf red coral platy started? Are you planning to breed them? 

My swordtail gave birth this weekend and i was able to separate 25+ fry. Will try to grow those out and keep the smallest male and female. 

Nope, no breeding planned. I would definitely choose the smaller males if I was going to breed--they are very attractive because they are proportional--none of the big belly, short back look of the dwarf platy, so I'd be interested to see if their offspring develop similarly. My current females are too old to breed and I cannot add more tanks at this time as I'm downsizing.