Abstract
The morphometric and meristic characteristics of 300 fish samples of silver catfish Chrysichthys nigrodigitatus (Lacepède, 1803) (Siluriformes: Claroteidae) inhabiting the Epe Lagoon, Lagos, was conducted between October 2012 and January 2013 in order to investigate the growth and health status of this species. The meristic characteristics deduced in this study were counted and ranged as follows; dorsal spine had constant value of one all through, and the pectoral spine had a constant value of two, dorsal rays were counted 6-7 (6.03 +/- 0.25), pectoral rays were counted 6-7 (6.04 +/- 0.27), gill rakers were counted 15-18 (17.86 +/- 0.96), opercula bones were counted 2-4 (3.22 +/- 1.11) and vertebrae count was 8-10 (8.43 +/- 1.95). All the morphometric characteristics except body weight were measured with measuring board of precision of 0.1 cm. Body weight was measured with a metler electronic chemical balance of precision of 0.1 g. Morphometric data includes total length 15.5-38.5 cm (25.43 +/- 3.87 cm), fork length 2.0-11.6 cm (8.61 +/- 1.53 cm), standard length 10.0-28.3 cm (17.85 +/- 3.90 cm), head length 2.0-3.5 cm (2.91 +/- 0.79 cm), head depth 1.0-3.3 cm (2.41 +/- 1.05 cm), eye diameter 0.5 1.0 cm (1.28 +/- 0.77 cm), body depth 1.6-6.5 cm (3.57 +/- 0.90 cm) and body weight 24.5-451.6 g (157.48 +/- 5.60 g). The length and the weight of this species were not directly proportional. Growth parameter has a negative allometric range (b = 0.256) and the condition factor (k) ranged from 0.103-2.97 (1.08 +/- 0.64) which indicated a good condition of the fish species in the Lagoon. This study provided baselines of the population structure of this species in Epe Lagoon, Lagos State and also shown that their present growth pattern calls for further monitoring.
Highlights
One of the most essential animal protein sources that complement predominantly carbohydrate based diets of Nigerian is fish (Akande, 2011)
The objective of the present study is to examine the growth and status of silver catfish in Epe Lagoon, Lagos, Nigeria, through morphometric and meristic characteristics of the species
Summary of meristic and morphometric characters of silver catfish from the study area showed that single dorsal spine and pectoral spine had constant values of 1 and 2, respectively, dorsal rays 6-7 (6.03 ± 0.25), pectoral rays 6-7 (6.04 ± 0.27), gill rakers 15-18 (17.86 ± 0.96), opercula bones 2-4 (3.22 ± 1.11) and vertebrae were counted 8-10 (8.43 ± 1.95) (Table 1)
Summary
One of the most essential animal protein sources that complement predominantly carbohydrate based diets of Nigerian is fish (Akande, 2011). Reports have shown that several methods can be effective in determining stock and scientific classification of fish, and one of the commonest method is morphometrc and meristic data (Gallo-da-Silva et al, 1998; Murta, 2000; Saborido and Nedreaas, 2000). Length and weight relationship (LWR) is a good method of growth assessment in fish (Arshad et al, 2012). A factor known as condition factor, has been reported to be effective in determining the physiological condition of fish and as well the status of the aquatic ecosystem in which fish live (Oni et al, 1983; Anyanwu and Ugwumba, 2003; Anene, 2005)
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