Need help theirs something wrong angelfish are acting really strange

Hi all I need help. I have been fish keeping for over 24 years now but I'm abit stumped at the moment. I have a pair off koi angelfish about the size off the Pam of your hand. I've had them from fry and are now about 2years old. They are in a 200liter tank on their own because they paired off quite a while ago. All my water conditions are fine. PH is fine .temperature is 80f.the problem is that I noticed the two off them have red blood streaks running along their back and fins.my female has stopped eating and I noticed this morning she seems very weak flopping over from tym to tym. I've been do water changes regularly for them but their seems no change. I've heard them clicking and taking like s shaking fit . I'm really stuck and worried I'm going to lose her. The male seems in better condition but has the same red blood streaks. Please if anyone has any advice it would be much appreciated. I've never seen this behavior in angelfish before. Thanks

Hard to judge from that description, but check the following....

1. I'm assuming you have tested the water since seeing the problems, if not test now.
2. Same for temperature, check that it is 80, and that includes double checking that the thermometer is reading accurately.
3. Do a 20% water change anyway, sometimes things get in to the water which don't show up on test kits.
4. check closely for signs of parasites, such as white spot or velvet, ideally use a magnifying glass to do this.
5. If no signs of parasites, I'd treat with octozin, especially if the fish appear at all bloated or to be breathing heavily.
6. I might also be tempted to treat with Esha 2000, either after the octozin course or even at the same time (not recommended by the manufacturer's, but in my experience absolutely fine)

Thanks for the reply. I've just lost my female angelfish in the last 5 minutes. I'm so annoyed with myself for letting something like this happen but I can't figure out how it happened. Yea I've checked everything over and over again and water and temp is all fine. I've upped my water changes all last week but they are still no change. I was going to try melafix. I hear so much about this treatment but is it any good do you no. Thanks for your help its much appreciated. I've never seen this before in all my years of fish keeping.

Sorry to hear you lost the female, she did sound pretty poorly.

I was going to try melafix. I hear so much about this treatment but is it any good do you no.

Yes, for some things, but it wouldn't be my first choice in this case.
I'd definitely use Octozin which is for protozoan infections, and if you want an antibacterial then Esha 2000, or myxazin. Melafix is good for supporting healing of damaged fins etc. once the initial crisis is past, it's a gentle, but slow acting treatment, so less effective in a crisis IMO.

Would I get octozin at my local pet store or would it have to be ordered.

I would expect it to be available from most aquarium stores, but not necessarily the average pet shop.

I just want to say a big thank you to pterophyllum for your help and advice. I tryed what you recommended and I know I loss my female but my big male seems to be back to perfect health. All red lines along dorsal fin are gone . his color is back and he's back to eating like a pig. Things could have been a lot worse if not for you my friend. Thanks

Glad you were at least able to save him & that he's looking well.