2.3. Surgical procedures
Fish were anaesthetized and placed belly-up in a ‘‘V’’ shaped
bed with an oral supply of dechlorinated and aerated water containing
anaesthetic (150–200 ppm). A ventral mid-sagittal incision
was made from the pelvic fin region towards the anal region. Circa
3–4 mm from reaching the anus opening the direction of the incision
was moved 120 to the right and proceeded for ca. 0.5 cm, in
order to expose the insertion of the gonads. In the castrated treatment
both testis were totally removed by a proximal incision. Given
the tight insertion of the testicular ducts with the urinary
bladder (Fig. 2), and to make sure that no vestigial testicular tissue
remained, the urinary bladder was always partially severed as a result
of the complete castration procedure. To control for this injury
during castration a control treatment was included consisting of a
partially sectioned urinary bladder only, in which 2 side cuts
(without tissue removal) were done 3 mm from the basis of the
insertion of gonads, without affecting gonadal functioning. In the
sham operated treatment, the ventral incision was made and sutured
without either castration or urinary bladder damage. In all
treatments the ventral incision was sutured using sterile synthetic
absorbable braided polyglycolic acid suture (USP 5/0, 3/8 circle DS
19 mm, Surgicril, Ref. 11101519). After recovery from anaesthesia
operated fish were returned to their experimental aquarium. No
mortalities or secondary infections were recorded.