Embryonic development of Eremophilus mutisii, “the captain of the savannah” (Pisces: Trichomycteridae)

Abstract

Eremophilus mutisii is a native, endemic species of the Colombian central highlands, with an emblematic character and characteristics that allow inferring some fish farming potential. In order to advance our knowledge about aspects related to its reproduction, embryonic development was monitored under controlled laboratory conditions. To this effect, wild and sexually mature specimens were induced with carp pituitary extract, in total doses of 5.5 mg kg^-1 in females and 4.0 mg kg^-1 in males, following protocols with demonstrated response. Fertilization was performed dry and incubation was carried out in glass vials of 3.6 L at 16.15 ± 1.1 °C. Samples were collected every hour from egg cells to hatching, and stages were established by means of stereoscopic observation and described with supporting photographic material. They are spherical, adherent eggs, with a diameter of 1052 ± 60.2 μm, telolecithal, and with meroblastic segmentation. For the stages of zygote, cleavages, blastocyst formation, blastula, gastrula, organogenesis, and hatching, description was done in 20 key moments, referenced temporarily in post-fertilization hours (PFH), degrees/hour (degrees h^-1), and degrees/day (degrees d^-1). Compared with other native catfish, the development period is considered extensive, with full hatching at 100 PFH (1615 degrees h^-1 387.6 degrees d^-1). The larvae were born with a total length of 3148 ± 176 μm, with a rounded yolk sac with a mean diameter of 0.9 ± 0.08 mm and a volume of 0.382 mm³.