Aggressive against female

Hi Scato

This behaviour is not really uncommon, – but there are of course two options, – which you mention yourself.
It can of course be another male, – and if so this male would probably, if smaller, not show too much colour. And if it is a young male, it may be difficult to see.
But it can also be a female. The ‘normal’ spawning behaviour will be that the male chases the female. This is part of stimulating the female to become ready to spawn.
If for some reason, the female does not become ready to spawn, – then of course the ‘chasing’ can become less good, – but many times it will end with the female becoming ready.

The important thing in this is that you have enough space, and hiding places in the tank that the fish, whether female or male, can stand the ‘chasing’ and get away and become ‘invisible for periods of time. And of course you have to monitor what happens, – and if it continues to not lead to the ‘female’ becoming interested, then perhaps you need to separate the fish. But normally, with enough hiding places, and a little bit of space, – paros will not harm each other at all. They are not like many other labyrints who really will almost kill each other, – not at all. But still of course its not optimal to have two males together in one tank.
When you are experienced, you would also be able to see on the male behaviour whether he is actually threathening, or trying to impress. If its another male, he will threaten, – he will not be so splendid in colours, he could turn much more dark, almost black – thats a sure sign. So look for that also.
Hope thats helpful.