Microscopic Evidence of the Opportunistic Reproductive Strategy and Early Sexual Maturation of the Small-Sized Characin Knodus moenkhausii (Characidae, Pisces)

Author(s)

Ceneviva-Bastos, M. ; Taboga, S. R. ; Casatti, L.

• Document type: Journal article
• Source: ANATOMIA HISTOLOGIA EMBRYOLOGIA; v. 44, n. 1, p. 9-pg., 2015-02-01.

Abstract

We investigated the reproductive biology of Knodus moenkhausii, an abundant small-sized characin fish with broad occurrence in the Parana River basin, Brazil. Specimens were collected monthly to determine fecundity, length at first maturity, reproductive period and spawning type. Gonads were macroscopically classified according to their form, size and texture in three different stages (immature, maturing or mature). Histological procedures were conducted to confirm gonadal developmental stages, and it was possible to notice that maturing females actually presented atretic oocytes, and all males that were macroscopically classified as immature, maturing and mature actually presented abundant spermatozoa in their gonads. Because of these discrepancies, a reclassification of gonadal maturations stages was needed after histological analysis, reinforcing its importance to studies on the reproduction of small characins. Reproduction occurred throughout the year though with two peaks. The length of the smallest mature individuals was 13mm SL for males and 24mm SL for females. Despite presenting relatively small batch fecundity, some life history traits such as early reproduction, multiple spawning throughout the year, in association with known opportunistic feeding habits, explain the high abundance of this species in locations where it occurs. (AU)

• FAPESP's process: 01/13340-7 - Evaluation of the biotic integrity of the rivers of the northwest region of the State of São Paulo, Alto Paraná basin, using communities of fish
• Grantee: Lilian Casatti
• Support Opportunities: BIOTA-FAPESP Program - Young Investigators Grants
• FAPESP's process: 04/12214-6 - Biology of Knodus moenkhausii (Teleostei, Characidae) in streams in the Alto Paraná: food, occurrence and reproduction
• Grantee: Mônica Ceneviva Bastos
• Support Opportunities: Scholarships in Brazil - Master
• FAPESP's process: 11/11641-1 - Effects of increasing structural complexity in degraded streams: detritus dynamics, energy flow, and food webs
• Grantee: Mônica Ceneviva Bastos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral