Abstract

The impact of fish feed on benthic invertebrates in channel catfish (Ictalurus punctatus) ponds was investigated. Benthic samples were collected from 10 catfish ponds, five in which fish were fed and five in which fish were not fed. The fed and unfed ponds were identical in design, management history and stocking density. Four benthic composite samples were collected from each pond monthly for three months and the invertebrates extracted and pH values determined. Fish feeding significantly reduced invertebrate taxa, abundance and the pH in fed ponds as compared to the unfed ponds. The mean pH in fed and unfed ponds was respectively 6.38 and 7.59; this represents an approximate 71 fold difference. Differences in the benthic invertebrate community seem therefore to be associated with pH levels. Fish feed reduced the populations of certain catfish parasites and this could partly account for the increased fish yield in fed ponds. Ecologically, the results reveal that fish feeding has a reductive effect on invertebrate taxa richness and taxa abundance. The results of this investigation seems to suggest fish feeding has a disruptive effect on the natural ecological functions and processes ascribed to benthic invertebrates, by significantly reducing their abundance, taxa richness, and altering the hydrogen ion concentration of the benthic environment.

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