I have 2 male red swordtails. They seem fine, swimming around, very active when it comes to feeding, but I suddenly noticed that their bellies seem bloated. As if they were pregnant or something. (Both are definitely males.)
The bloating seems even on both sides and could even be considered normal looking, nothing odd, but my fish seemed much... slimmer before.
I just added an activated carbon insert to my filter a couple of hours ago and those white absorbing ceramic cylinders (not sure what they are called).
All was carefully rinsed before being added. The old filter mediums are still in it, so I hope bacteria within didnt suffer.
About 10 mins before dealing with the filter I fed the fish live blood worms. I fed them the worms before on multiple occasions and they loved them. This time was no exception.
Whatever the cause, what can be done against bloating?