Frecked website has just voted for the 10 most beautiful fish species in the world. Notably, there is also the appearance of Nudibranch sea slugs and mantis shrimps. 1. Poinsettia fish. 2. Emperor pomfret. 3. Lionfish. 4. Marble fish. 5. Nudibranch sea slug. 6. Discus fish. 7. Mantis shrimp. 8. Fish…