I got 6 mickey mouse platy's about a month ago. They were all doing good, except one. This one platy kept sitting on the gravel most of the time and about every 5 minutes it would swim all the way up and release some bubbles at the surface and would immediately go back down. When it swims up to the surface it looks like it struggles to swim(almost like swimming against a strong current). It got a little better after a few days...started to actually swim around but still would crash on the bottom and looked like it struggled to swim. The platy eats every single time I feed the fish.
About two days ago it started to get worse again. The platy would just sit on the bottom all day long and would swim up to the surface to release some bubbles. I decided to put the platy in one of my 12gal plastic buckets that I use for water changes. I have a little power filter attached to the bucket and also a heater to keep the temp. the same as it was in the tank. The platy has been in this bucket for 2 days now and no improvement. Still crashes at the bottom and only swims up to the surface every now and then...but it still eats like it's healthy.
I also noticed that it's body is slightly curved to the left? I don't know what's wrong with it so I don't know how to treat it.
The water in the tank the platy was in seems to be good. 0 ammonia, 0 nitrite, 7.5 pH and the temp. is around 78 degrees. I have the same temp. going on in the bucket the Platy is currently in. Also keep testing the water in the bucket and it's all good...0 ammonia, 0 nitrite, pH is a little higher though...closer to 8.0. I change 50% of the water every other day in the bucket...but that's as far as I got as far as treating it since I have no idea what's wrong with it.
What can I do? Does it sound like it's not getting enough oxygen? damaged gills? gills disease