During the past decade, the European Union established an ecosystem-based management approach in inland and Atlantic waters. The implementation of this strategy, which aims to more effectively protect the aquatic environment across Europe, is mostly accomplished through two main EU legal instruments, the Water Framework Directive 2000/60/EC (WFD) and the Marine Strategy Framework Directive 2008/56/EC (MSFD). Under both directives, the use of sentinel organisms with distinct genetic make-ups, spanning several trophic levels, is expected to play a key role in the definition of the ecological and environmental status of inland and marine waters. Hence, especially in marine areas, there is a need to validate new sentinels ready to be used in the assessment of environmental stress, including anthropogenic pollution. Teleost fish are particularly interesting given the available knowledge on their genetic background, with many homologies to that of mammals. Additionally, a robust knowledge on the biology and ecology of several teleosts is already available. Here, we revise the information on the distribution, habitat, life history and reproduction of two families of teleost fish, Blenniidae and Syngnathidae, particularly focusing on marine and estuarine species that have already been shown to adequately respond to xenobiotic insults. Special emphasis is given to the revision of literature that supports the use of both families as sentinels for pollution monitoring. Gaps in current knowledge are also identified and potential research priorities established.