180liters thats like a 55gallon if im not mistaken so thats fine... looks like plenty of hiding spots.. if it gets worse rearrange the tank again .. i have to change mine up about every month ... im gonna state the obvious which you prolly already know but its recommended not to mix the lakes although i dont think thats your problem... and the blood parrots should really be rehomed as they arent africans and sooner or later its gonna cause a problem in your tank.
Anyhow keep a eye on your tank if the problem continues or gets worse try rearranging your tank see if that helps