Phenotypic Colour Variants in Batches of Fingerlings of Clarias gariepinus from Some Commercial Fish Hatcheries

Abstract

Aims: This research seeks to determine the ratio of dark skin and pale skin coloured fingerlings in batches of fingerlings produced in commercial African catfish hatcheries in Makurdi, Nigeria.
 Study Design: The study was designed based on a structured questionnaire that was administered to farmers that were selected using random sampling from a list of African catfish farmers.
 Place and Duration of Study: The research was carried out in Makurdi town, Makurdi Local Government Area of Benue State, Nigeria. Data collection was done between October 2021 and January 2022.
 Methodology: The current study used a blend of questionnaire and physical counting to determine the proportion of dark and pale offspring from five selected fish hatcheries in Makurdi, Local Government Area of Benue State. A sample of 140 to 300 offspring was made upon each visit to the farm (i.e. batch of production) with each farm being visited at least twice depending on the production timetable.
 Results: Results show that the farms normally incubated a similar weight of egg (p>0.05) with the range between 258g to 550g in each batch of production. The number of fry produced was scaled to 90% and it ranged from 165075 to 351450. Percentage of dark hued offspring ranged from 80% to 86% while that of pale offspring was between 14% and 20%. There was no correlation between turbidity and the colour classification. There was no significant difference between the farms in terms of incidence of dark or pale hued fingerlings suggesting that the colour proportion is constant within batches of fingerlings.
 Conclusion: Dark skin colour is dominant over pale skin colour in the African catfish Clarias gariepinus and water quality does not predict skin colour in this species under culture.