Space size relative to prey width and total cover in an area both influence the habitat choices of freshwater angelfish Pterophyllum scalare in mesocosms

Abstract

Prey survivorship can vary with average space size/prey width (Sp/Py) and total cover within an area (Ct/At). Hypotheses predict that prey survivorship is maximized at intermediate Sp/Py values and that prey survivorship increases rapidly from zero to low cover but increases at a slower rate as cover increases further. Freshwater angelfish Pterophyllum scalare made choices between artificial vegetation treatments consistent with these predictions. At constant low cover, fish did not exhibit any space width preferences. At constant medium cover, fish significantly preferred a narrower space treatment over a wider space treatment. At constant high cover, fish significantly preferred a wider space treatment over narrower space treatments. At constant Sp/Py, fish exhibited a marked preference for a higher-cover treatment at low-cover levels. They also preferred higher cover treatments under higher cover levels, but these preferences were not as pronounced. Sp/Py and Ct/At both influenced the fishes’ habitat choices.