A Study of the Catfishes of Lekki Lagoon, With Particular Reference to the Species Chrysichthys Walker. (Bagridae)
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The resident fish population in Lekki Lagoon and the physical features of the environment were investigated. A total of 15 families comprising 28 species were recorded in the lagoon. The ecology of the three catfishes that account for about 42.5 percent of the total catch in the lagoon was studied. An investigation of age and growth revealed that Chrysichthys walkeri attained a maximum length of 25.7cm, over a period of less than two years. Chrysichthys filamentous and Chrysichthys nigrodigitatus comprised mostly of young-of-the-year fish, a pointer to the problem of overfishing in the lagoon. There were no significant differences in the growth pattern of the catfishes during the dry and rainy seasons. Certain differences were found in the food habits of the three species of catfish Ch. walkeri fed mostly on chironomid larvac Ch. filamentous mostly on ostraceds and Ch. nigrodigitatus had nolluses as major foods items. The spawning habits and fecundity of Ch. walkeri were investigated. This species bred for most part of the year from September to June. Fecundity estimates ranged from 896 to 4,168 eggs. The average number of eggs per female was 2,084. A racial study of Ch. nigrodigitatus from both Lagos and Lekki Lagoons showed that they were not genetically separable populations. There were however statistically significant differences in the number of gill rakers. It is suggested that the differences resulted from environmental fluctuations, for example, differences in salinity gradients in the two lagoons. The fishing methods in the lagoon were examined. A pilot scheme that could yield nearly 200 tons of catfish in its first year of operation is proposed for Lekki Lagoon, the introduction of catfish farming in Nigeria is also suggested.