Platy problem

[NatalieAnna]

Hello all,

I'm new here and was wondering if anyone could help please.
I bought a tank around 3 months ago and 2 months ago added 4 platies. We added otos a few weeks ago.
The black one in the pictures seems to be acting odd. He keeps resting on things, lying down a lot and not moving anywhere near as much as normal. He's a lot smaller than my other platies. I've checked all tank parameters and it all seems fine, he's the only one acting off and has been this way for a couple of days now. At feeding time he's happy and swims around but other than that he rests a lot.
Is there any advice on how I can help him?

 

[Colin_T]

Hi and welcome to the forum

The black fish has clamped fins and looks like it has excess mucous on its head (creamy film on its noggin). this is usually caused by poor water quality or something in the water irritating the fish. It can also be stress related if the fish is being bullied by other fish (the bigger yellow and orange platy).

-------------------
What sort of filter is on the tank?
How often and how do you clean the filter?

Is the fish eating well?
What does the fish's poop look like?

-------------------
Check the water quality for ammonia, nitrite, nitrate and pH. Post the results in numbers here.

Post some pictures showing the entire tank so we can check the habitat.

Monitor the other fish and see if any go over and pick on the black one.

Do a 75% water change and gravel clean the substrate every day for a week.
Make sure any new water is free of chlorine/ chloramine before it's added to the tank.