Platy is very skinny compared to other platys?

I have a 29 gallon planted tank that is fully stocked. There are 8 platys in it plus a couple more species.

One of my females (one of the first platys I got) looks somewhat skinnier than the other females and swims erratically sometimes. I also witnessed her nipping at other fish near a hole in some driftwood, like she was hiding there and didn’t want anyone else in there with her. She wasn’t in the driftwood though, she was just hanging around the area. She is usually pretty laid back though and doesn’t mind the other fish. I’ve seen her clamping her fins a lot lately also and she swims near the top frequently. Not sure if it’s because she’s just shy or if she is actually sick.

She’s very shy and unlike my other fish when I (gently) put a finger on the glass she backs away, usually the others will come up and check it out, and maybe even follow my hand. The newer platys do this too but I figured it’s because they are still adjusting to their new tank.

Should I be concerned? I have a small tank that I am getting ready for a betta fish that I can temporarily use as a quarantine tank for right now if she needs it.

I’ve added pictures! A few side pictures and one from the top.

Thanks in advance!

Edit: forgot to mention when she’s not being shy and acting weird, she acts normal and is pretty active and energetic. She is also eating normally.

 

I have a 29 gallon planted tank that is fully stocked. There are 8 platys in it plus a couple more species.

One of my females (one of the first platys I got) looks somewhat skinnier than the other females and swims erratically sometimes. I also witnessed her nipping at other fish near a hole in some driftwood, like she was hiding there and didn’t want anyone else in there with her. She wasn’t in the driftwood though, she was just hanging around the area. She is usually pretty laid back though and doesn’t mind the other fish. I’ve seen her clamping her fins a lot lately also and she swims near the top frequently. Not sure if it’s because she’s just shy or if she is actually sick.

She’s very shy and unlike my other fish when I (gently) put a finger on the glass she backs away, usually the others will come up and check it out, and maybe even follow my hand. The newer platys do this too but I figured it’s because they are still adjusting to their new tank.

Should I be concerned? I have a small tank that I am getting ready for a betta fish that I can temporarily use as a quarantine tank for right now if she needs it.

I’ve added pictures! A few side pictures and one from the top.

Thanks in advance!

Edit: forgot to mention when she’s not being shy and acting weird, she acts normal and is pretty active and energetic. She is also eating normally.

Fish typically never clamp their fins, at least not consistently if they're healthy. Could be bullying since she's a female, it's recommended to have 3 females for every male Platty, or the male's can stress the females out until death. If you don't really notice any bullying, it sounds like internal parasites to me. Have you ever caught her pooping, if so, what does it look like? Could be absolutely nothing, some fish are just a lot more reclusive than others, but it's worth being concerned over.

 

Fish typically never clamp their fins, at least not consistently if they're healthy. Could be bullying since she's a female, it's recommended to have 3 females for every male Platty, or the male's can stress the females out until death. If you don't really notice any bullying, it sounds like internal parasites to me. Have you ever caught her pooping, if so, what does it look like? Could be absolutely nothing, some fish are just a lot more reclusive than others, but it's worth being concerned over.

There are 2 males and 6 females, and I’ve really never seen any male or any other fish bothering her. She poops frequently just like every other platy in my tank haha. What should poop look like? It sinks to the bottom pretty quickly and is brown.

 

There are 2 males and 6 females, and I’ve really never seen any male or any other fish bothering her. She poops frequently just like every other platy in my tank haha. What should poop look like? It sinks to the bottom pretty quickly and is brown.

Is it stringy at all? White, green, yellow? Is it consistently Brown and solid? If so, there shouldn't really be nothing to worry about.

 

Is it stringy at all? White, green, yellow? Is it consistently Brown and solid? If so, there shouldn't really be nothing to worry about.

Normally when I see her poop its brown and solid. I’ll keep an eye on her for the rest of the day and I’ll get back to you

 

I honestly can’t really recall. I’ll keep an eye on her for the rest of the day and I’ll get back to you

Sounds good! If it is normal, the fin clamping and signs of irritation could just be a sign of a parameter problem and she's displaying irritation because of it, so keep an eye on those parameters as well.

 

Sounds good! If it is normal, the fin clamping and signs of irritation could just be a sign of a parameter problem and she's displaying irritation because of it, so keep an eye on those parameters as well.

Do you recommend any test kits? I’m pretty sure my API one is inaccurate.

 

Do you recommend any test kits? I’m pretty sure my API one is inaccurate.

IMO, my best luck is with API, I find that people commonly don't test properly. For example, the nitrate test you really have to shake that bottle for a minute, and mix properly for a few minutes at a time. 100% for me I just have to be patient with it, some Test Strips are reputable but inconsistent for me, personally.

 

IMO, my best luck is with API, I find that people commonly don't test properly. For example, the nitrate test you really have to shake that bottle for a minute, and mix properly for a few minutes at a time. 100% for me I just have to be patient with it, some Test Strips are reputable but inconsistent for me, personally.

Thanks, I’ve heard of people saying the ammonia test tends to show some ammonia when in fact there is none, but if you leave it for a few hours it shows 0. My test kit shows no nitrates even though my tank has been up for almost 3 months. I made a post a few days ago here and on Reddit and some people said the reason my test kit is showing no nitrates is because my plants are sucking it all up.

My other fish seem to be fine, no signs of illness and no abnormalities. But I guess it is possible that this particular fish is just more sensitive than the others. I’ll keep an eye on her. Thanks!