Fecundity and food habits of the slender stonebasher (Hippopotamyrus ansorgii Boulenger, 1905) (Mormyridae) in Ogbese river

Abstract

Fecundity study is important in order to evaluate the reproductive potentials of fish species. Thus, fecundity and food habits of Hippopotamyrus ansorgii (H. ansorgii) from Ogbese river were investigated. Total of 32 specimens of H. ansorgii were used. The major fishing method employed for collecting the specimens were cast and gill netting. Fecundity and food habits the fish were studied. The total lengths ranged from 14.6 cm to 22.1cm while the body weights ranged from 30.0 to 91.0 g. The food items found in the examined stomachs were rotifer, algae, insects, crustacean, detritus and plant parts but the major food items based on the ranking index were insects and crustaceans. The sex ratio of H. ansorgii was 1.13: 1 for males: females. The gonadosomatic index showed that H. ansorgii in Ogbese river uses an average of 11.69% of its body weight in egg production. Fecundity ranged from 600 to 7200 eggs with an average of 3231 eggs per female. In conclusion, H. ansorgii in Ogbese river was an omnivore and highly fecund fish.

A review of the reproductive biology of mormyroid fishes: An emerging model for biomedical research

“…As an individual progresses through the reproductive cycle, gonadal somatic index (GSI) fluctuates. GSI has been measured in several mormyroid species including Brienomyrus longianalis (Ikomi, 1996), Gymnarchus niloticus (Opadokun & Ajani, 2015), Hippopotamyrus ansorgii (Odedeyi & Odedire, 2017), Hyperopisus bebe occidentalis (Oniye & Onimisi, 2010), Marcusenius senegalensis (Adjibade et al, 2020), Mormyrus kannume (Khallaf & Authman, 2012), Mormyrus rume proboscirostris (Kirschbaum et al, 2008; Schugardt & Kirschbaum, 2004), and Pollimyrus isidori (Crawford et al, 1997). However, many authors do not report the phase of the reproductive cycle during which measurements were made and therefore comparison of these measurements is confounded.…”

“…As an individual progresses through the reproductive cycle, gonadal somatic index (GSI) fluctuates. GSI has been measured in several mormyroid species including Brienomyrus longianalis(Ikomi, 1996), Gymnarchus niloticus(Opadokun & Ajani, 2015), Hippopotamyrus ansorgii(Odedeyi & Odedire, 2017), Hyperopisus bebe occidentalis(Oniye & Onimisi, 2010), Marcusenius senegalensis(Adjibade et al, 2020), Mormyrus kannume(Khallaf & Authman, 2012), Mormyrus rume proboscirostris…”