Objective: Diabetes can be controlled with insulin injections, but a curative approach that restores the number of insulin-producing β cells is still needed. Methods: Using a zebrafish model of diabetes, it screened ~50 seaweed crude extracts to identify enhancers of β cell regeneration. Results: The extracts identified converge on the bone morphogenesis protein (BMP) signaling pathway that inhibit endogenously BMP signaling. The most potent enhancer of β cell regeneration was the Polysiphonia japonica (PJ), which, acting through the BMPRΠ, increased β cell proliferation in zebrafish. Despite markedly stimulating β cell proliferation during regeneration, PJ had only a modest effect during development. Conclusion: With this whole-organism screen, it identified component of the BMP pathway that could be therapeutically targeted for the treatment of diabetes.