New on this, I got a tank with two discus and three angel fish, I have read that at least ones a month we need to remove parasite from fish but I donīt know what to usu for that, could you recomend me something!
You read that once a month you need to treat your tank for parasites? That's not true.
Are your discus and angels showing any signs of disease or illness?
Prazipro (praziquantel) is typically used for deworming fish of tapeworms, but will not kill all types of worms or nematodes. It can kill flukes but if not used for an extended aggressive treatment will not kill fluke eggs so then the problem comes back once the lifecycle completes. Most fish respond well to praziquantel treatment and I have used it to treat for possible tapeworm and unsuccessfully treated for flukes. Did not kill the eggs.
It's really best to treat for diseases that you physically are seeing signs of in your fish. White feces, flashing, clamped fins, not eating etc. First rule out basics like ammonia poisoning, water parameters, being a newly introduced fish in your tank and needing an adjustment period, tank mates picking on them etc.
Fish have immune systems as we do that can handle disease and may show no signs of illness, but may in fact be sick. When you start treating randomly with medications you can do more damage than good. They can compromise the fish's immune system. Medications cause a lot of stress on the fish. If your treating with the wrong meds that do nothing but weaken your fish's immune system the disease/parasite they might actually have can take a better grip on your fish and kill them. Leaving you guessing what the hell happened. So sometimes its best to not just throw meds in your tank unless you really know what's causing your fish's illness.
If your going to be keeping very expensive and larger species of fish such as discus I'd recommend buying a microscope. You can do skin and gill scrapes of your fish to find flukes, test feces for parasites etc. It's one of the best things I ever bought and i've been able to identify issues and treat them accurately. Proper quarantine procedures with these fish that so commonly carry pests is important to prevent harm to healthy stock.