Demersal fish assemblages are intimately associated with benthic habitats where they spend a large part of their time feeding and avoiding predators. Bottom fishing activities can degrade seabed habitats and change benthic communities by reducing their complexity. Thereby they can also degrade essential fish habitats such that they can no longer sustain the fish species associated with them. Having established a relationship between cod (Gadus morhua) and whiting (Merlangius merlangus) and specific Irish Sea habitats from consultation with fishers and ground fish surveys we wanted to learn what functional role these habitats play, i.e. as sources of prey and shelter from predators. Habitats complexity of stations with high and medium fish densities was assessed using side scan sonar, QTC ViewTM and underwater photography. Young cod were particularly abundant in a habitat with mixed sediments (low grain size sediments between stones and shells) and emergent epifauna off Belfast Lough (Northern Ireland). Dietary specialism indicates a close association with a particular habitat, while broader diets within and between different areas indicate a weaker association of a fish species with a particular habitat. The availability of prey organisms was assessed by sampling epifaunal and infaunal organisms with a 2-m beam trawl and a Day grab. Demersal fish for condition and stomach contents analysis were collected by otter and beam-trawling. The results from stomach content analysis of cod and whiting are discussed in relation to the prey availability found in the study areas and food niche breadth.