Experimental protocol
The experiment started on the day following capture and was repeated on
three consecutive days for all fish (trial 1-3). Each fish was removed
from its home tank using a small hand-net and transferred the short
distance (~1.5m) to the experimental tank where it was
placed in a release compartment at one end of the tank. The release
compartment was 30x40cm and darkened using black plastic on all sides
and top covering. As soon as the fish was in the release compartment an
opaque plexiglass divider was lifted by 5cm allowing the fish access to
the main arena. The main arena was 60x40cm with all sides covered with
blue and green aquarium background (plant patterned) preventing the
experimental fish from seeing outside the tank. The main arena was
visually divided in three equal areas by black lines on the bottom of
the tank. Four food patches were placed within the arena each with two
bloodworms taped to a small glass petri dish. Two of the patches were
sheltered by a round of four small stones and two were unsheltered. The
food patches were in areas two and three while the first area, closest
to the release compartment, was empty (Fig. 1). The water level in the
experimental tank was 10cm with continuous flow of aerated and chilled
(12.0°C) water. The behavior of fish in the experimental tank was
videoed from above for 10-min. From the 10-min videos recorded we
extracted (1) latency to explore, i.e. the fish fully moved out of the
release tank; (2) latency to forage, the time to locate and attempt to
feed at any of the food patches and (3) activity, the number of times a
fish fully crossed between the three areas in the tank. It was also
noted if feeding took place at an open or sheltered food patch.