The Marine Stewardship Council (MSC) has continued to strengthen its position in the market based on its credibility as a transparent, accountable and science-based third party certification scheme. However, the consolidation of MSC's credibility risks being undermined by the poor representation of developing world fisheries and concerns that the scheme provides little incentive for continual improvement for fisheries once certified. This paper argues that the challenge of maintaining credibility while increasing access and fisheries improvement constitutes a ‘devils triangle’. In the absence of a clear policy from MSC for balancing this triangle fisheries are taking their own actions to differentiate themselves both above (MSC-plus) and below (MSC-minus) the certification threshold. To avoid further undermining of the MSC the organisation should internalise such externally-led differentiation by moving towards an internally controlled tiered certification system based on its already existing metric-based principle indicator system. Doing so would communicate on equity and continual improvement both before and after certification, and create on-going incentives for fishers to enter into the MSC programme.