Coral aquaculture is undergoing a massive expansion to meet the demand of emerging reef restoration activities and the ornamental trade. However, aquaculture production of corals, particularly sexually propagated individuals, still requires much development to be cost-effective at scale. As such, many novel solutions are being explored to boost production and reduce costs, one of which is co-culture. Similar to integrated aquaculture, this is the practice taking advantage of existing symbiotic relationships between animals by culturing corals with one or more organisms that can provide different services. Commonly explored applications of co-culture include the use of microherbivores to control algae growth in coral recruit grow-out, the addition of various pest and parasite predators to help control outbreaks, and the use of companion fish as a source of nutrient enrichment. While small-scale trials have been performed, and shown positive results, large-scale trials taking into account the cost-effectiveness of these methods compared to more traditional approaches have yet to be undertaken. As such, here we summarise the current state of co-culture research in coral aquaculture, and suggest avenues for future research to explore.