Diet of Gambusia affinis holbrooki, Xiphophorus helleri, X. maculatus and Poecilia reticulata (Pisces: Poeciliidae) in Streams of Southeastern Queensland, Australia
Level 5 - mechanism / opinion, no new human data
Level 5 by Oxford CEBM rules (animal research / non-human ecological study).
OpenAlex W4313194765 · doi:10.33997/j.afs.1989.2.2.006
What was done
The diets of four introduced poeciliid fish species (Gambusia affinis holbrooki, Xiphophorus helleri, Xiphophorus maculatus, and Poecilia reticulata) were examined in subtropical streams in southeastern Queensland, Australia. Ingested prey items were identified and analyzed relative to fish mouth gape and environmental prey availability.
What was found
The four species showed significantly different mean diet compositions. Gambusia affinis fed primarily on terrestrial prey (ants and adult nematoceran Diptera) and some aquatic Hemiptera; prey eaten were small relative to gape (mean prey width 0.3 x mouth gape, mean length 1.28 x mouth gape) and environmental availability (mean prey ingested = 0.597 x mean length and 0.702 x mean width of available prey), while abundant benthic taxa (e.g., immature Trichoptera, Ephemeroptera, Oligochaeta, Crustacea, Mollusca) were eaten infrequently. Xiphophorus helleri was omnivorous (plant tissue, algae, and invertebrates). Xiphophorus maculatus consumed crustaceans (dominated by the atyid shrimp Caridina) and insects. Poecilia reticulata had a diverse diet mostly consisting of terrestrial insects (particularly ants) and chironomid larvae.
Why it matters
This study documents clear dietary partitioning among co-occurring invasive poeciliid fishes and identifies the specific food resources utilized, providing baseline trophic data to assess potential competition with native Australian freshwater fish.
Limits
The abstract does not report the total number of fish sampled, number of stream sites, sampling frequency, or confidence intervals. Impacts on sympatric endemic fishes were discussed conceptually rather than quantified directly.
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