Gonadal recrudescence and induced spawning inBarbus altianalis

Abstract

Gonadal recrudescence in Barbus altianalis from River Nile, Jinja (33°05E; 0°45N) Uganda was studied prior to induced spawning. Oocytes in B. altianalis were found to develop in cohorts suggesting batch spawning throughout the year with pronounced spawning activities coinciding with rainfall peaks of April and September. There was a strong positive correlation between rainfall and gonadosomatic index (r S = 0.75, P = 0.008). B. altianalis had low fecundity (6.0 AE 2.0 per gram) and large-sized eggs (2.97 AE 0.1 mm). Induced spawning was successful with exogenous hormones and water current. Results from this study suggested that total striping may not be appropriate, but larger eggs would confer high survival of offsprings under optimal conditions. The success registered in induced spawning of B. altianalis provides a breakthrough in seed production for multiplication and culture of this economically important fish species.

Effectiveness of African catfish pituitary extracts, dagin and water flow for optimising egg production, fertilisation and hatchability in artificial spawning of Barbus altianalis

“…The very high variation in fertilization and hatchability rates observed during induced spawning (Table 2) may be reflective of the varying levels of egg maturation in B. altianalis. Barbus altianalis is a batch spawner with eggs developing in batches one after the other (Rutaisire et al, 2015). In the event of induced spawning, the egg batches do not ripen at the same time.…”

“…The regular availability of this seed is essential for closing the life cycle of fish in captivity (Funge-Smith and Phillips, 2001;Stickney, 2005). Fish species have an inherent mechanism that relates to the gonadal structure and activity with appropriate environmental stimuli that triggers spawning (Munro, 1990;Rutaisire et al, 2015). Under appropriate environmental stimuli relayed to the brain through the neuron system, sustained levels of releasing hormone (GnRH) from the hypothalamus, triggers the release of luteinising hormone (LH) and follicle stimulating hormones (FSH), that control oocyte maturation and ovulation (Peter and Yu, 1997;Levavi-Sivan et al, 2010).…”

“…The pituitary extracts become an alternative cheaper source and readily available option to the farmers than the synthetic hormones. In the initial artificial spawning experiments, ovulation in wild B. altianalis broodstock was successfully facilitated by water flow (Rutaisire et al, 2015). The effectiveness of water to induce spawning could be linked to the maturation level of gravid individuals, whereby water flow facilitated increased hormonal release levels by encouraging courtship and excitement.…”

Histo-morphological description of the digestive system of the Rippon Barbel Barbus altianals (Boulenger 1900): A potential species for culture

“…In sub-Saharan Africa there is growing need to diversify and promote the culture of indigenous high-value fish species to increase fish production (Namulawa et al, 2011;Rutaisire et al, 2013;Kato et al, 2014). Efforts were successful in artificially inducing one of the high value indigenous cyprinid, B. altianalis, to spawn (Rutaisire et al, 2013). However, concern arose due to its slow growth rates that could partly be attributed to a knowledge gap of its feeding behavior.…”

“…A number of cyprinids in Africa are potentially highvalue species that are being ever exploited, and can only be salvaged through culture. Successful domestication and subsequent commercial culture of B. altianalis, will increase fish production and revenues for commercial farms in the region (Rutaisire et al, 2013). The cyprinids, commonly referred to as carps, are regarded as stomachless fish though with a diversity of structural and functional modifications of the digestive system (De Silva and Anderson, 1995).…”