Once the marine larval stage is complete, amphidromous gobies tend to gather at the mouth of fresh water streams.  It is believed that entering this low salinity environment triggers morphological changes, primarily to the shape of the head and orientation of the mouth, as they begin their juvenile life-history stage.  The post-larval juveniles often recruit into the rivers en mass with pulses of large schools of fish swimming upstream toward their adult habitat.  For many species the preferred adult habitats are only found in the upper reaches of streams and rivers, which on volcanic islands may require climbing up to 600 m above sea level in a matter of only 10s of kilometers.  These rivers are typically fast flowing over rocky substrate and often have a number of waterfalls between the mouth and the headwaters.  Juvenile amphidromous gobies are very well adapted to climb even the tallest of waterfalls, some as high as 100 m.  Using their specialized ventral fins, which have evolved into a circular suction-cup like appendage on their abdomen, they are able to stick to the shear face of most moist surfaces.  With an undulating motion these young gobies inch their way up and over these vertical barriers and reach preferred adult habitats in a matter of days to weeks, depending on the species.