This Gelodok fish (Mudskipper) which is called as amphibious fish have unique activity that can live in terrestrial and aquatic area. This study aims to study the daily activities of fish population 2 types of Periophthalmus variabilis and Boleophthalmus boddarti by using the scan sampling method and ad libitum. This research was conducted in September 2017 at the mouth of the river Tluwuk, Pati, Central Java. Observations were made for 150 minutes with a time interval of 5 minutes. The results showed that fish activity P. variabilis (v) was different from B. Boddarti (b).  P. varibilis spends more time on land (90%) than in water (10%) whereas B. Boddarti activity is more in water (60%) than in land (40%). Observed activities are walking (a = 24,08 %., b = 11,73% ), jumping (a = 4.01%, b = 0.65%), feeding / catching prey (a = 5,01%, b = 7.82%), swimming (a = 2.01%, b = 11.72%), moving dorsal fins (a = 4.01%, b = 3.26%), moving caudal fins (a = 2 , A = 2.67%, b = 7.82%), escape predators (a = 3.34%, b = 6.51%), head movements (a = 4.01%, b = 15.63%), entering holes/nesting (a = 0.67%, b = 1.95%), and inactive (a = 40.13%, b = 19 , 54%).