Robust microbiomes are often shaped by symbiotic host-microbe relationships. Multi-strain symbioses forming when multiple strains of the same bacterium successfully colonize a host are prevalent in animal-microbe relationships, but certain molecular mechanisms influencing microbial competition during their establishment remain poorly understood. This research seeks to characterize interactions between three co-isolated strains of bioluminescent marine bacterium Vibrio fischeri in vitro, revealing more about factors underlying the formation of multi-strain symbioses in similar model systems.