The yellow platy pictured seems to be bullying the others. Mixed genders. Should I be worried? I have no way to separate them unfortunately. Sadly I lost a male last week and there wasn’t even a corpse so I’m wondering if she ate him?!
Yes it is, I posted on here last week because the deceased fish was swimming up on the surface almost acting strange.
A test showed levels were all pretty good apart from nitrates so I did a 75% change on Sunday to attempt to rectify that. All other fish very healthy and even have 2 fry swimming about that have been born in the last few days.
The red male platy is stressed, has clamped fins and covered in excess mucous. This is usually caused by poor water quality or something in the water irritating the fish.
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.
In the wild, female livebearers hang out in large groups consisting of between 20 & 50 (but sometimes up to 100 or more) females. These groups have a pecking order with the biggest most dominant female ruling the group and she has a group of girlfriends who back her up. All the other females live in the group but are lower down the pecking order.
The groups of females move around rivers and waterways looking for food and places to hang out. As the groups move around a few males follow the group and try to breed with any females. The groups of males have a pecking order too and the biggest male will bully his smaller mates.
Your female platy is top dog and is bullying the smaller weaker fish.