Reproductive behaviour, developmental morphology and sexual dimorphism in <scp>T</scp>aranetz's lumpsucker, <scp><i>Eumicrotremus taranetzi</i></scp> (<scp>C</scp>ottoidei: <scp>C</scp>yclopteridae) – A long‐term aquarium study

Spawning behaviour, ontogenetic development and sexual dimorphism of the Taranetz's lumpsucker Eumicrotremus taranetzi are described based on aquarium observations. Reproductive behaviour was observed from ca. 1000 days after hatching [dah, female ca. 45.0 mm body length (BL), male ca. 37.0 mm BL], including territorial males remaining on the artificial substrate after spawning and protecting eggs until hatching. Some of the eggs were moved to a smaller tank for hatching. Eggs hatched approximately 110 days after spawning at an average water temperature of 2.8°C. Pelvic-fin sucker formation begins in the egg at 83 days (completed at 90 days) after fertilization (daf). Newly hatched larvae have a smooth body (without spines or bony tubercles), fully developed fins (except for the caudal fin) and adhesive suckers. Larvae attach themselves to the bottom or side of the tank immediately after hatching. Bony tubercles on the body appear first on the head at 50 dah. Males and females exhibited distinct sexual dimorphism in 15 body measurements and the number of bony tubercles at 200 days post hatching (dph), probably related to the egg-guarding behaviour of males.