Abstract:

Barbus altianalis is an indigenous cyprinid that lives in lacustrine-riverine environments with limited
distribution to Upper Victoria Nile and lakes Victoria, Edward, George and their associated rivers.
I he species is a delicacy in Uganda and surrounding regions and also vulnerable to overexploitation.
B. altianalis is cultured by very few farmers and the biggest challenge has been lack of seed for its
commercial propagation. This study was conducted to determine optimal spawning conditions, larval
weaning, juvenile growth and survival with a view of producing mass quality seed for propagation.
Two field and 17 lab/pond experiments were conducted to improve hatchability, growth and survival
of larvae and juveniles. Results showed that fish for spawning is best picked at > 30-34.9 cm and 35-
39.9 cm fork lengh for males and females, respectively. Fish treated with African catfish pituitary
extracts (ACPE) performed slightly better than those treated with Dagin. However, the differences
between females treated with ACPE and Dagin were not significant with respect to working
fecundity (2314.40; 1207.37), fertilisation rates (80.27; 40.80%) and hatchability (42.20; 27.44%) at
p > 0.0167 respectively. ACPE are equally effective and cheaper for inducing B. altianalis to spawn.
Working fecundity and hatchability were significantly higher when only ripe running females were
stripped after 4 hours (100 degree hours) of flashing water than those stripped after lOhrs (250 degree
hours) at 25°C. Optimal temperature for embryo hatchability was 24°C - 27°C. Hatchabity was good
and the same (p > 0.05) between re-circulating (84.3%) and glass tank systems (80.3%). High larval
growth (158.61 ± 1.56; 195.03 ± 2.71mg) and survival (81.24± 1.55%; 78.96 ± 2.04%) were attained at 30°C and 27°C, respectively. The digestive tract of B. altianalis was simple and valveless and was
xix
on average 2.22 ± 0.37 times longer than its body length. It showed a strong ability to utilize and
assimilate every diet but also showed preference of food items at early stages becoming all inclusive
in its diet as it matures. Larval ontogeny of digestive structure and related enzyme activity confirmed
that microdiets were acceptable at exogenous feeding (6-7 Day after hatch-DAH). But better growth
and survival were obtained with a combination diet {Moina + microdiet). Hence, outdoor larvae
nursing and microdiet manipulations for better growth and survival were successful^ ^.15 DAH.
When prevalence of aquatic parasites was anticipated, outdoor nursing and or stocking were delayed
until after or during larvae scalation process at 48 - 75 DAH. This study has now been able to
determine the optimal spawning and growth performance conditions of larvae and juveniles in B.
altianalis and it will now be possible to produce mass and quality seed for propagation.