Acts as an electroneutral and low-affinity sodium (Na(+))-dependent sodium-coupled solute transporter. Catalyzes the transport across the plasma membrane of many monocarboxylates such as lactate, pyruvate, nicotinate, propionate, butyrate and beta-D-hydroxybutyrate. Expressed in brain and eye 24, 72 and 120 hours post-fertilization (hpf). At 72 hpf expressed in swim bladder and in pronephric tube. At 120 hpf expressed in brain, trabecular bar, eyes, otic capsule, stomach, gall bladder, gut and pancreas. Belongs to the sodium:solute symporter (SSF) (TC 2.A.21) family.