Greylorn by Keith Laumer, Science Fiction, Adventure, Fantasy, Space Opera

A scourge called the Red Tide is devouring the planet. The only hope of the dying population is to find a lost colony in the stars. However the starship sent to find that colony has a problem. Mutiny! Commander Greylorn must bravely deal with a discouraged crew . . . And then even a bigger problem. Dreadful aliens called the Mancji living in a high-G environment who seem to have developed a taste for human flesh.