Complex sentence: It is relatively uncommon to find monogamous relationships in fish, amphibians and reptiles; however, the red-backed salamander as well as the Caribbean cleaner goby practice monogamy as well.
Split into simpler sentences: It is relatively uncommon to find monogamous relationships in fish, amphibians and reptiles. However, the red back salamander as well as the Caribbean cleaner goby practice monogamy as well.