Background. Morphology of eggs and embryonic development of the genus Coryphopterus are documented for the first time. The species C. venezuelae, C. dicrus, C. eidolon, and C. thrix have been found to have a similar ecology, but details about their reproduction are still unclear. The aim of the present study was to investigate if egg morphology, mode of attachment, and development differ between the species; which could be attributed to use of different microhabitats and/or resources. Materials and methods. Fish were kept in aquaria and their eggs were collected every 6 h. Embryonic development in the eggs was documented under a dissecting microscope. Additionally egg morphology and mode of egg attachment were studied by a scanning electron microscope. Results. The time of embryonic development was 66 h in all species. Egg dimensions were 0.7–1.1 mm in length and 0.3–0.5 mm in width. The eggs were attached to the substrate by an adhesive apparatus typical for gobiids, a net like structure around the micropylar pole, and composed of filaments, 1.5–2.2 μm in diameter. The zona radiata was of 0.5–0.8-μm thick. Conclusion. No differences in the period of embryonic development, egg shape or means of attachment could be found between the species studied, but variations in egg dimensions and their attaching structures were noted. The zona radiata is very thin in comparison to other fish eggs, though comparative data of fish with a similar ecology are needed.

Coryphopterus, embryonic development, scanning electron microscope, egg morphology, zona radiata