In August 2023, we conducted a fish survey around Platform Holly and at two nearby seep tents, in southern California, using a remotely operated vehicle. We divided the structures into four habitats: Platform Holly midwaters, Platform Holly base, seep tents towers, and seep tents bases. The platform and the seep tents are similar in the following ways: 1) all are fabricated of steel, 2) all are in approximately the same bottom depth, 3) all are physically close together (and thus in the same water mass and likely exposed to the same current patterns), and 4) all were surveyed within a three-day period using the same methodology. They differ in that, compared to the other three habitats, the seep tent bases are more complex, having numerous ledges and holes. Over all four habitats, we observed a minimum of 36 fish species, representing 6,541 individuals and, at all habitats, the vast majority of fishes were rockfishes (Sebastes spp.). In addition, most of the fishes were small, and the majority at all sites, were juveniles. However, unlike at the other habitats where only juveniles were found, at the more complex seep tents bases we observed large, mature fishes of several species (e.g., copper and vermilion rockfishes). Based on these observations, we hypothesize that adding complexity to the bottom of Platform Holly, as part of the decommissioning process, will increase the density of large, mature fishes, particularly of those species that are usually associated with sheltering sites.