Hi there, It seems I need to explain this as simple as possible for you to understand.
Blood parrots are freshwater fish, when freshwater fish enter saltwater they die. How? Blood parrots adapt and evolved in freshwater, and the salt in saltwater causes the water in the blood parrot to leave. No water in blood parrot = dead. Saltwater fish, adapt and evolved to saltwater, so that water does NOT leave their body. When they enter freshwater, too much water enters their body, and their organs explode. What happens if a fish adapts to salt and freshwater? You get fish like Monodactylus.