Author(s): ROTTA, M. A.; RODRIGUES, R. B.; PEDROSO, M. F.; ACORCI FILHO, L. C.; LARA, J. A. F. de; STREIT, D. P.

Summary: Abstract: The banded knifefish Gymnotus cf. carapo (Pisces, Gymnotidae), also known locally as tuvira, is a natural resource of great importance to the Pantanal biome that has been used as live bait in sport fishing. This study investigated the mass synchronization of gonadal development of banded knifefish in captivity by subjecting them to different water electrical conductivity at different time intervals (pre and post conductivity change) and also evaluated the use of ultrasound imaging to identify the sex and phases of ovarian recrudescence of the captive broodstock. Fish were exposed to three different combinations of time intervals (Group 1: 40 + 30 days; Group 2: 45 + 25 days; Group 3: 50 + 20 days) and water conductivity (high: 180 ?S/cm, followed by low: 15 ?S/cm conductivity, respectively). The control group was kept in low water conductivity throughout the 70-day trial. Based on the results, 93%, 94%, and 86% of mass gonadal maturation of Gymnotus cf. carapo could be achieved by keeping the fish in high water conductivity (180 ?S/cm) for 40, 45, or 50 days, and subsequently in low conductivity (15 ?S/cm). The sexing and maturation assessment of the fish using ultrasound imaging was fundamental for effectively evaluating the mass gonadal maturation protocol. The combined use of these techniques proved safe in reproductive studies with banded knifefish.

Publication year: 2023

Types of publication: Journal article

Unit: Embrapa Pantanal

Keywords: Gymnotus Carapo, Peixe, Reprodução Animal, Tuvira