Individual carp horizontal cells express up to four different connexins. The expression of Cx49.5 and Cx52.6 in carp horizontal cells was confirmed via in situ hybridization and RT–PCR. Cx55.5 and Cx53.8 form dendro-dendritic and axo-axonal gap junctions between carp horizontal cells. Cx55.5 hemichannels are present on horizontal cell dendrites invaginating cone pedicles. Identified horizontal cell connexins are duplicated in carp.