Strange "Mini" Platy

Hello everyone!
So I've had this fish for about a month now. She (at least I'm pretty sure it's a she) is very small compared to my others. She also just swims in one place almost all of the time and rarely moves. The other platys stay together and swim around together but she just stays by herself. She is about the size of an adult neon tetra. She eats fine, can get around fine, doesn't lay on the bottom and her poop is normal. She has never been bullied by any of the others in the tank, they all leave her alone. All of the water parameters are normal too. Any ideas what is up with her? Is she just younger than the others or is this a deformation? Is there something else going on? Any questions or suggestions are welcome. Also, I have 3 other male platys in the tank with her and I fear they might breed (I don't want that). I do have a 10 gal that has a very peaceful betta in it, would that be a better fit for her and prevent her from breading?

Water parameters:
Ammonia: 0
Nitrite: 0
Nitrate: 10
pH: 7.5
Temp: 77
Size: 29 gal
Other fish: 4 platys, 3 males and the fish in question, 6 neon tetras.

Thanks for the help!

BTW the picture below, there is a small white spot on the gill of the fish, that is just the way the light shines on it plus my not very good phone camera, it is not there in person

Neleono said:

Hello everyone!
So I've had this fish for about a month now. She (at least I'm pretty sure it's a she) is very small compared to my others. She also just swims in one place almost all of the time and rarely moves. The other platys stay together and swim around together but she just stays by herself. She is about the size of an adult neon tetra. She eats fine, can get around fine, doesn't lay on the bottom and her poop is normal. She has never been bullied by any of the others in the tank, they all leave her alone. All of the water parameters are normal too. Any ideas what is up with her? Is she just younger than the others or is this a deformation? Is there something else going on? Any questions or suggestions are welcome. Also, I have 3 other male platys in the tank with her and I fear they might breed (I don't want that). I do have a 10 gal that has a very peaceful betta in it, would that be a better fit for her and prevent her from breading?

Water parameters:
Ammonia: 0
Nitrite: 0
Nitrate: 10
pH: 7.5
Temp: 77
Size: 29 gal
Other fish: 4 platys, 3 males and the fish in question, 6 neon tetras.

Thanks for the help!

BTW the picture below, there is a small white spot on the gill of the fish, that is just the way the light shines on it plus my not very good phone camera, it is not there in person
View attachment 130981

Click to expand...

She might just be young, If you don’t want them breeding maybe you can give her to a LFS, or set up a tank with only females.

It could have intestinal worms and or gill flukes.

Did you buy it or is it baby from one of your fish?

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Try treating them all for intestinal worms and see if it helps.

Livebearers like guppies, mollies, swordtails & platies are regularly infected with gill flukes and intestinal worms. If the fish are still eating well but losing weight, then worms is the most likely cause.

You can use Praziquantel to treat tapeworm and gill flukes. And Levamisole to treat thread/ round worms. If you can't find these medications, look for Flubendazole, which treats both lots of worms.

Remove carbon from filters before treatment and increase aeration/ surface turbulence to maximise oxygen levels in the water.

You treat the fish once a week for 4 weeks. The first treatment will kill any worms in the fish. The second, third and forth treatments kill any baby worms that hatch from eggs inside the fish's digestive tract.
Treat every fish tank in the house at the same time to prevent cross contamination.

You do a 75% water change and complete gravel clean 24-48 hours after treatment. Clean the filter 24 hours after treatment too.
Do not use the 2 medications together. If you want to treat both medications in a short space of time, use Praziquantel on day one. Do a 75% water change and gravel clean the substrate on day 2 & 3. Treat the tank with Levamisole on day 4 and do a 75% water change and gravel clean on day 5, 6 & 7 and then start with Praziquantel again on day 8.

The water changes will remove most of the medication so you don't overdose the fish the next time you treat them. The gravel cleaning will suck out any worms and eggs that have been expelled by the fish. Repeating the treatment for 3-4 doses at weekly intervals will kill any worms that hatch from eggs. At the end of the treatment you will have healthier fish.

Neleono said:

Hello everyone!
So I've had this fish for about a month now. She (at least I'm pretty sure it's a she) is very small compared to my others. She also just swims in one place almost all of the time and rarely moves. The other platys stay together and swim around together but she just stays by herself. She is about the size of an adult neon tetra. She eats fine, can get around fine, doesn't lay on the bottom and her poop is normal. She has never been bullied by any of the others in the tank, they all leave her alone. All of the water parameters are normal too. Any ideas what is up with her? Is she just younger than the others or is this a deformation? Is there something else going on? Any questions or suggestions are welcome. Also, I have 3 other male platys in the tank with her and I fear they might breed (I don't want that). I do have a 10 gal that has a very peaceful betta in it, would that be a better fit for her and prevent her from breading?

Water parameters:
Ammonia: 0
Nitrite: 0
Nitrate: 10
pH: 7.5
Temp: 77
Size: 29 gal
Other fish: 4 platys, 3 males and the fish in question, 6 neon tetras.

Thanks for the help!

BTW the picture below, there is a small white spot on the gill of the fish, that is just the way the light shines on it plus my not very good phone camera, it is not there in person
View attachment 130981

Click to expand...

She does look "wrong" to me, but I can't tell whether a deformity/internal problem from birth/genes, or wasted somewhat from internal parasites. I'd move her away from the male platies (although it may be too late, ) because a female livebearer among males will breed, no question. You can't keep them together and hope it won't happen. Not good to breed a deformed fish, both because we don't want to be passing on those bad genetics in future generations, lowering the quality of these fish overall, and because a deformed female trying to birth fry is much more likely to die in the process.

I'd go with Colin's advice to worm them all, especially if they've never been wormed, livebearers are so prone to carrying worms. If she doesn't catch up after that, then it's probably some internal genetic/birth defect.

I have a young guppy that was born with a prolapsed bowel, managed to get some photos of her the other day:


I don't know whether I separated her from her brothers in time before her potentially getting knocked up - crossing fingers she didn't, since I don't think she'd survive a birthing, and I hate having to cull fry. If she is, I won't let any of her offspring go into the general gene pool. I considered culling her when I saw the prolapse as a fry, but she was a fighter and I couldn't do it. So she's now in my female only tank. She's maybe 2/3rds the size of other females from her batch, but otherwise appears to be healthy! So she can live out her life in my girl tank. Sometimes, birth defects happen.

Ok, I'll start the deworming as soon as I can get to the store and pick up the meds. Thanks everyone for the advice!