Mariculture is viewed by some as an unsustainable economic activity in marine protected areas (MPAs). Surprisingly, no study has confirmed or rejected the veracity of the view. In Indonesia's multi-purpose MPAs, mariculture is considered as part of the local communities' livelihood and resilience strategy. This study aimed to determine whether small-scale fish farming, along with small-scale fisheries and eco-tourism, contributes to the livelihood sustainability of communities in Indonesia's small island MPAs, and if the practice is compatible with the overall MPA objectives. The study was conducted in the Anambas Archipelago MPA and interviewed 66 respondents from three household groups (small-scale fish farmers, fishers, and eco-tourism operators) from 15 villages. A closed- and open-ended questionnaire was developed to determine the sustainability profile of each livelihood group. The questionnaire consisted of 75 questions representing the sustainability indicators (SIs) of the five capital assets described in the Sustainable Livelihoods Framework (SLF). The SIs were measured using a Likert-scale and a Likert-type scale with multiple scales. The data were standardised using linear transformation and aggregated to calculate the SIs composite values. The study found that the livelihood sustainability of the small-scale fish farmer group is comparable to small-scale fisher and tourism operator groups. Interestingly, the fish farmer group outperformed the other two groups in relation to human capital assets by developing a strong social network. Small-scale fish farmer, fisher and eco-tourism operator groups have a composite sustainability index value of 0.55, 0.61, and 0.50, respectively, categorised as intermediate sustainability. This study concluded that the sustainability profile of each livelihood group could be improved for the specific underperforming capital assets by increasing support from the government and MPA authority.