Offshore Oil & Gas (O&G) infrastructure creates artificial reef complexes that support marine communities in oceans. No studies have characterized the first wave of colonization, which can reveal information about habitat attraction and ecological connectivity. Here we used opportunistically-collected industrial Remotely Operated Vehicles (ROVs) to investigate fish and invertebrate colonization on a new North Sea O&G platform and trenching of an associated pipeline. We observed rapid colonization of fish communities, with increases in species richness (S), abundance (N), and diversity (H′) over the first four days (the entire study period). By contrast, there was minimal change in motile invertebrate communities over the survey period. After trenching, invertebrate S, N and H′ decreased significantly, whilst fish S, N and H′ increased. This study is the first to report on the pioneer wave of fish and invertebrate colonization on O&G infrastructure, thereby providing rare insight into formation of new reef communities in the sea. These short and opportunistic data are valuable in terms of showing what can be discovered from analysis of ‘pre-installation’ ROV footage of O&G structures, of which there are terabytes of data held by O&G companies waiting to be analyzed by environmental scientists.