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Optimal hatching condition protocols on B. altianalis seed production in Uganda

Optimal hatching conditions of Barbus altianalis have been identified in a study in Uganda to pave the way for its commercialization. “These results will guide farmers to produce sufficient and quality B. altianalis seeds for farming,” authors Aruho et al. cited.

Experiments focused on critical embryonic stages impacted by temperature, light, water depth, aeration and hatching facility suitable for hatchability, growth and survival of B. altianalis embryo and larva. The study was published on Journal of the World Aquaculture Society.

B. altianalis is commonly known as Kisinjja in Uganda and ripon barbel in the US.

“It is imperative for hatchery managers to ensure that temperature is strictly controlled or regulated at the late embryonic stages in order to maximize egg survival during egg incubation period,” they stressed. It was observed that compared to the other stages during incubation, the late embryo stage was affected at each temperature treatment.

Optimum hatchability at over 80 per cent was achieved at 24 C without aeration and 27 C with aeration.

Aeration was found to negatively impact embryo development. “The present study established that direct bubbling of air led to mechanical agitation that disrupted embryo development and largely affected especially late embryo stage,” they said. Use of recirculating plastic tank and glass systems mitigated the problem.

Circular tank system, glass tank system and conical-shaped jars were used in the hatching facilities. Circular tank system posted the highest hatchability rates but not significantly over that of the tank system, both above 80 per cent. Hatchability in conical jars, however, was significantly lower at 37 per cent

Increasing temperature from 27 C up to 30 C resulted in optimum development of B. altianalis larvae. “This temperature range should be considered for integration into the spawning protocol for this newly domesticated species, B. altianalis,” they said.

Domestication of the freshwater species is new and an offshoot of declining population in the wild, spurred by high market demand. While artificial spawning has been successful, seed production has been hampered by a number of challenges, including high mortalities during egg incubation and larval development.