The 'opae kuahiwi, or mountain opae, prefer the higher sections of the streams where there is abundant cool, clear and fast-flowing water. The other is the prawn, 'opae oeha'a, and is most common in the lowest stream section in slow-flowing water. The other two species can mostly be found at the mouth of rivers. Most native Hawaiian stream animals share a unique life cycle pattern, called amphidromy. The most common example are the salmon and eels, which are commonly given as examples in nature books and shows.
Adults live in streams as adults.
The gobies lay their eggs in the stream, and upon hatching, the larvae migrate downstream and are swept out to sea. After living in the ocean plankton community for a time, the postlarvae, called hinana, return to the adults habitat by migrating upstream, often climbing numerous waterfalls. Unlike the salmon, the gobies do not return to the streams that they were born in. Maintaining the natural patterns of water flow in streams is the single most important requirement for protection of native Hawaiian stream animals. These natural flows will keep the river mouth open and provide the gateway for our precious native stream animals to complete their life cycle.