Marine　toxins　from　microscopic　algae　can　accumulate　through　the　food　chain　and　cause　various　neurological　and　gastrointestinal　illnesses　for　human　health.　Herein,　we　designed　a　new　ultrasensitive　multiplexed　immunoassay　protocol　for　simultaneous　electrochemical　determination　of　brevetoxin　B　(BTX-2)　and　dinophysistoxin-1　(DTX-1)　in　seafood　using　distinguishable　metal　nanocluster-labeled　molecular　tags　as　traces　on　bifunctionalized　magnetic　capture　probes.　To　construct　such　a　bifunctionalized　probe,　monoclonal　mouse　anti-BTX-2　(mAb(1))　and　anti-DTX-1　(mAb(2))　antibodies　were　co-immobilized　on　a　magnetic　bead　(MB-mAb(1,2)).　The　distinguishable　metal　nanoclusters　including　cadmium　nanoclusters　(CdNC)　and　copper　nanoclusters　(CuNC)　were　synthesized　using　the　artificial　peptides　with　amino　acid　sequence　CCCYYY,　which　were　used　as　distinguishable　signal　tags　for　the　label　of　the.　corresponding　bovine　serum　albumin-BTX-2　and　bovine　serum　albumin-DTX-1　conjugates.　A　competitive-type　immunoassay　format　was　adopted　for　the　online　simultaneous　monitoring　of　BTX-2　and　DTX-1　on　a　homemade　flow-through　magnetic　detection　cell.　The　assay　was　based　on　the　stripping　voltammetric　behaviors　of　the　labeled　CdNC　and　CuNC　at　the　various　peak　potentials　in　pH　2.5　HCl　containing　0.01　M　KCl　using　square　wave　anodic　stripping　voltammetry　(SWASV).　Under　optimal　conditions,　the　multiplexed　immunoassays　enabled　simultaneous　detection　of　BTX-2　and　DTX-1　in　a　single　run　with　wide　working　ranges　of　0.005-5　ng　mL(-1)　for　two　marine　toxins.　The　limit　of　detection　(LOD)　and　limit　of　quantification　(LOQ)　were　1.8　and　6.0　pg　mL(-1)　for　BTX-2,　while　those　for　DTX-1　were　2.2　and　7.3　pg　mL(-1),　respectively.　No　non-specific　adsorption　and　electrochemical　cross-talk　between　neighboring　sites　were　observed　during　a　series　of　procedures　to　detect　target　analytes.　The　covalent　conjugation　of　biomolecules　onto　the　nanoclusters　and　magnetic　beads　resulted　in　good　repeatability　and　intermediate　precision　down　to　9.5%.　The　method　featured　unbiased　identification　of　negative　(blank)　and　positive　samples.　No　significant　differences　at　the　0.05　significance　level　were　encountered　in　the　analysis　of　12　spiked　samples,　including　Sinonovacula　constricta,　Musculista　senhousia,　and　Tegillarca　granosa,　between　the　multiplexed　immunoassay　and　commercially　available　enzyme-linked　immunosorbent　assay　(ELISA)　for　analysis　of　BTX-2　and　DTX-1.