Características do sêmen de tambaqui (Colossoma macropomum) em latitude equatorial

Abstract

The Amazonian fish known as tambaqui (Colossoma macropomum Cuvier, 1818) is a osseous fish and has high commercial value because of its meat quality and for recreational fishing. Tambaqui is one of the major species in the Amazon basin and found in most rivers and surroundings of Manaus city (Silva et al., 1984). The present study was carried out to evaluate sperm parameters from tambaqui, subjected or not to hormone treatment for a period of 12 months. We used 26 males with three years of age, raised at the Aquaculture Research Center of the National Department for Drought Control (DNOCS). Animals were identified with magnetic chips and divided into two groups: controls (NI) and hormone-treated (I), which received 2 mg of carp pituitary extract (CPEkg-1) of body weight (via intra celomic). Semen was collected 14 hours after hormonal induction and the following parameters evaluated: volume, pH, osmolarity and sperm concentration. Fishes had body weight of 5410 g, with total length and standard length of 68 cm and 59.17 cm, respectively. In the case of hormone-treated and control animals, we found the following criteria, respectively: semen volume of 5.05 mL and 0.55 mL (p<0.05); pH of 8.21 and 8.09; osmolarity of 320.51 and 323 mOsm/kg; sperm concentration of 22.93 x 109 and 40.46 x 109 sptz/mL (p<0,05). Total sperm productions were quantified as 115.79 x 109 sperm/mL in treated fishes and 22.25 x 109 sperm/mL in the controls. We conclude that treatment of adult tambaqui with carp pituitary extract increase semen volume but reduces sperm concentration while had no effect on sperm osmolarity and pH.