Odd Platy behaviour - could be an illness?

A couple of my Platys behave very differently to the rest and even look a bit different so I did consider they might not be Platys after all.

Both hide most of the time and tend to have clamped fins. The also have flat bellies, unlike the normal rounded ones of the others. In theory, all the Platys in the tanks should be males as that's what I asked for - I don't want a population explosion or cannibalism!

Both the odd Platys are the smallest of the bunch.

In another thread about a problematic Rainbow fish:

https://www.fishforums.net/threads/active-and-ravenous-but-thin-with-long-stringy-poop.454375/

..the possibility of a protozoan infection was mentioned.

Both the odd Platys eat and apart from the strange flattened bellies and behaviour, they don't look 'sick' but I am a bit worried about them.

I'll try to snap some photos later today.

Comments or advice is most welcome!

So here is one of my timid hide-away Platys with a flat belly. I could not find the other one as it was hiding. Both fish look very different to the others.

It's a boy but it does have clamped fins and tail. Not badly clamped but they are clamped a bit. However, I think the clamped fins are a side effect of whatever is wrong with the fish and not the main issue.

What does the skinny platy's poop look like?

Are the platies in the same tank as the rainbowfish from your other thread?
If not are you treating all your tanks for worms?
You want to treat every tank in the house for intestinal worms (at the same time), so there is no cross contamination.

Livebearers (platies, guppies, swordtails, mollies) are regularly infested with intestinal worms and gill flukes. The Flubendazole you are using on the rainbows should work on the platies too.

-------------------------
You can treat gill flukes and some protozoan infections with salt, and it works well on livebearers and rainbowfish.

You can add rock salt (often sold as aquarium salt), sea salt or swimming pool salt to the aquarium at the dose rate of 2 heaped tablespoon per 20 litres of water.

If you only have livebearers (guppies, platies, swordtails, mollies), goldfish or rainbowfish in the tank you can double that dose rate, so you would add 4 heaped tablespoons per 20 litres.

Keep the salt level like this for at least 2 weeks but no longer than 4 weeks otherwise kidney damage can occur. Kidney damage is more likely to occur in fish from soft water (tetras, Corydoras, angelfish, gouramis, loaches) that are exposed to high levels of salt for an extended period of time, and is not an issue with livebearers, rainbowfish or other salt tolerant species.

The salt will not affect the beneficial filter bacteria but the higher dose rate will affect some plants. The lower dose rate will not affect plants.

After you use salt and the fish have recovered, you do a 10% water change each day for a week using only fresh water that has been dechlorinated. Then do a 20% water change each day for a week. Then you can do bigger water changes after that. This dilutes the salt out of the tank slowly so it doesn't harm the fish.

If you do water changes while using salt, you need to treat the new water with salt before adding it to the tank. This will keep the salt level stable in the tank and minimise stress on the fish.

@Colin_T After I took the photo I saw that there were two spots on its tail - so it's a derivative of the 'mickey mouse' Platy variant but the flat belly, odd behaviour and even the somewhat rounded rather than flattened head did make me wonder if this wasn't a Platy at all at first.

Both the odd Platys do eat although they still try to avoid the others during feeding. The others do seem to chase them.

I haven't noticed any unusual poop issues with either of them. I've only had the one pictured about a month but the slightly smaller one not pictured has been in the tank for some time.

I only have one tank

The 2 skinny fish might be getting bullied by the others and this will continue until they die or are moved to another tank.

Livebearers (platies, swordtails, guppies, mollies) have a pecking order with dominant males bullying smaller weaker males. And dominant females do the same to smaller weaker females. Once the pecking order is sorted out things are usually fine but sometimes it doesn't settle down and the weaker fish die from stress caused by bullying and starvation.

If you have a couple of breeding nets you could move the weaker ones into those nets and see if they improve. Otherwise wait until you have finished treating the tank and if they haven't improved, rehome them.

Good idea thanks.